| 单词 | calcite |
| 例句 | There are quarries all over the country where you can find calcite, quartz and pyrite. Chemical Compounds That Incite Oohs and Aahs 2022-06-24T04:00:00Z Everything is preserved by the thinnest layer of calcite from the water oozing out of limestone over the millennia. Herzog's Cave of Forgotten Dreams: the real art underground 2011-03-17T23:00:01Z Aloha From Hanalei also sells jewelry made from Kauai calcite, one of the only gemstones found on the island. Journeys: Finding Hawaiiana To Take Home, on Kauai 2010-06-11T18:32:00Z Ten miles from Custer and named for its calcite crystals, the Jewel Cave is the third longest cave system in the world with 200 miles of tunnels. Head for the Black Hills: tales of Crazy Horse and Custer in South Dakota 2018-11-18T05:00:00Z Jewelry and art have long captivated both collectors and the general public, but recently, fine minerals — topaz, quartz, calcite and more — have also been figuring in. Chemical Compounds That Incite Oohs and Aahs 2022-06-24T04:00:00Z The figure of King Khafre, who reigned from 2576-2551 B.C. and built the Great Sphinx and the second largest pyramid at Giza, presides at the entrance: a statue of seemingly glowing calcite alabaster. 'Tutankhamun' in Seattle: artifacts both dazzling and humble 2012-05-25T05:42:18Z In many places the calcite is fashioning stalagmites on the ground, glossy nubs that appear translucent white in the center. Under the Shenandoah Mountains, a West Virginia caving adventure 2019-04-04T04:00:00Z Deciphering the chemical composition of each individual page—each thin, calcite layer—gives scientists a diary of the seawater through which the animal journeyed as it built its shell. Barnacles could help solve the mystery of Malaysian Airlines Flight 370 2023-08-23T04:00:00Z It’s a desolate alluvial fan on the southern flanks of the Cady Mountains, where sparkling calcite crystals and pieces of quartz, jasper and agate are continually carried down the slopes by thunderstorms and flash floods. Rockhounds fight for access to their jewel in the desert: Mojave Trails National Monument 2023-07-16T04:00:00Z Yellow crystals, including calcite, are associated with vital energy and sensuality, according to Keshu. Create a more calming home with a DIY meditation space 2023-01-24T05:00:00Z This calcite's crystallized form reflects changing Ice Age water levels in a cave in southern China. New Classification Reveals Just How Many Ways Minerals Form 2022-09-05T04:00:00Z The calcite typically comes from limestone quarries like the one on Texada Island, B.C. Physical Geology 2015-01-01T00:00:00Z Note the double-refracted word “calcite” in the center of the figure due to birefringence. An Introduction to Geology 2017-01-01T00:00:00Z The researchers, including experts from Johannesburg and France, examined radioactive decay in rocks buried at the same time as the fossils, whereas earlier estimates were based on calcite flowstone deposits. Fossils in South African cave reignite debate on origins of humankind 2022-06-29T04:00:00Z Over time, these skeletal fibers decayed, leaving hollow tubules that filled up with calcite crystals. 890-million-year-old fossils may be oldest sign of animal life on Earth, Canadian geologist says 2021-07-29T04:00:00Z You can clearly discern the individual calcite plates, or ossicles, that made up the skeletal frames of these animals when they were alive. 'Squiggly wiggly' fossils rise from a Jurassic sea 2021-07-21T04:00:00Z The limestone, which is primarily made up of the mineral calcite, has been dissolved to different degrees in different areas because of compositional differences. Physical Geology 2015-01-01T00:00:00Z Some carbonate rocks, such as calcite and dolomite, are formed via evaporation and precipitation. An Introduction to Geology 2017-01-01T00:00:00Z In 1894 a miner named James Roach broke into a cavern 80 feet beneath Joplin, Mo. The walls, ceiling and floor were lined with crystals of calcite, a form of carbonate. Why Geology Is Our Destiny 2021-06-22T04:00:00Z Yet bats were blocked from the innermost parts of Azé by a thick plug of calcite around 22,000 years ago. Why Did the Cave Art Vanish? It Was Erased by This Furry Creature and Its Feces. 2021-06-17T04:00:00Z Investigators in Canada found Teck Resources Limited discharged hazardous amounts of selenium and calcite into the Fording River from two coal mines north of Eureka, Montana, the Missoulian reported Sunday. Canadian coal company pays $60M for environmental damage 2021-03-29T04:00:00Z Quartz veins are common in this situation, and they might also include pyrite, hematite, calcite, and even silver and gold. Physical Geology 2015-01-01T00:00:00Z Because they polarize light, calcite crystals are used in special petrographic microscopes for studying minerals and rocks. An Introduction to Geology 2017-01-01T00:00:00Z Among the discoveries was a 7-millimeter-long artifact made from a mineral called calcite, the team reports today in the Journal of the Royal Society Interface. Atom smasher unearths surprises hidden with 2000-year-old mummy 2020-11-24T05:00:00Z As he stepped carefully along the slick and uneven surface, his headlamp illuminated ruffled curtains of stone and walls popcorned with kernels of calcite. How Humanity Unleashed a Flood of New Diseases 2020-06-17T04:00:00Z Scientists were able to study deposits of calcite, a mineral, during the excavation of the cave, nearly 19 miles south of Lisbon. Neanderthals ate dolphins and seals, researchers reveal 2020-03-27T04:00:00Z Some of the important chemical weathering processes are hydrolysis of silicate minerals to form clay minerals, oxidation of iron in silicate and other minerals to form iron oxide minerals, and dissolution of calcite. Physical Geology 2015-01-01T00:00:00Z Solid calcite reacts with hydrochloric acid by effervescing or fizzing. An Introduction to Geology 2017-01-01T00:00:00Z They found the calcite on a pig began forming at least 43,900 years ago, and the deposits on two buffalo were at least 40,900 years old. Animal painting found in cave is 44,000 years old 2019-12-12T05:00:00Z Blue sodalite for peace, pink calcite for love and tangerine quartz “for life energy to wish them well into the next life,” said Grayson’s father, Jeff, 59. Despite rain, L.A. County turns out to remember its unclaimed dead 2019-12-04T05:00:00Z On the strong side of the tooth, resilient calcite fibers provide a supportive wall. Rock-munching sea urchins have self-sharpening teeth 2019-09-18T04:00:00Z Depending on the pressure, temperature, and chemical conditions, these crystals might include calcite, hematite, quartz, clay minerals, or a range of other minerals. Physical Geology 2015-01-01T00:00:00Z Some evaporites and carbonates, like salt and calcite, are more prone to this reaction; however, all minerals can be dissolved. An Introduction to Geology 2017-01-01T00:00:00Z When calcite forms, impurities often get caught in the gaps, or end up replacing the calcium atom, in a process known as substitution. Ancient plankton have climate data hidden in their shells 2019-01-31T05:00:00Z They showed that the calcite layers were youngest at the surface and oldest closer to the paintings, meaning the dating is sound, Aubert says. This animal image may be the world’s oldest figurative art 2018-11-07T05:00:00Z On the other side, the calcite materials are arranged in brittle inclined plates, which chip away as the tooth scrapes against materials like starfish and rocks, leading to a constantly sharp edge. Rock-munching sea urchins have self-sharpening teeth 2019-09-18T04:00:00Z Beneath that depth, calcite is soluble so limestone does not accumulate. Physical Geology 2015-01-01T00:00:00Z The figure shows a cave formation created from dissolution followed by precipitation—groundwater saturated with calcite seeped into the cavern, where evaporation caused the dissolved minerals to precipitate out. An Introduction to Geology 2017-01-01T00:00:00Z That method focused on boron-11, a different element, in shell calcite. Ancient plankton have climate data hidden in their shells 2019-01-31T05:00:00Z Buried objects retained more color, but often pigments were hidden beneath accretions of dirt and calcite, and were brushed away in cleanings. The Myth of Whiteness in Classical Sculpture 2018-10-22T04:00:00Z The same chemical reactions also reduce the availability of calcite and aragonite, two carbonate minerals that are needed for the shell-building process. CO2 is killing the ocean, too 2018-09-13T04:00:00Z All of the dolomite found in ancient rocks has been formed through magnesium replacing some of the calcium in the calcite in carbonate muds and sands. Physical Geology 2015-01-01T00:00:00Z Ardisol forms in dry climates and can develop layers of hardened calcite, called caliche. An Introduction to Geology 2017-01-01T00:00:00Z As cyanobacteria make sugars from sunlight and CO2 in the water, they trigger the formation of calcite—the same mineral that can form stalagmites and stalactites in caves. 6 Amazing Structures Built by Surprising Creatures 2018-05-07T04:00:00Z Take an arresting, 4-foot-tall anthropomorphic figure carved from calcite marble, which stands in a stiff, inflexible pose. Teotihuacan: An ancient Mexican city's remarkable art comes to life at LACMA 2018-04-18T04:00:00Z The calcite formation in many caves in the region are of "great, outstanding beauty and absolutely match the ones seen elsewhere seen," says Mr Arbenz. Secrets of a world record-breaking 'fairy cave' 2018-04-14T04:00:00Z For example, calcite is soluble in dilute acid and will give off bubbles of carbon dioxide. Physical Geology 2015-01-01T00:00:00Z The components include aragonite, a mineral similar to and commonly replaced by calcite, and silica. An Introduction to Geology 2017-01-01T00:00:00Z In and of themselves, coral reefs are extraordinary living structures: vast calcite scaffolds constructed by billions of tiny polyps. 6 Amazing Structures Built by Surprising Creatures 2018-05-07T04:00:00Z Multiple translucent crystals fit the bill, namely calcite, cordierite and tourmaline. The Crystals That May Have Helped Vikings Navigate Northern Seas 2018-04-06T04:00:00Z All three types of crystals that the team studied—calcite, a form of calcium carbonate; cordierite, an iron- and magnesium-rich silicate; and tourmaline, a boron-rich silicate—worked well at intervals of 3 hours or less. Viking seafarers may have navigated with legendary crystals 2018-04-03T04:00:00Z When it forms, the calcite crystals tend to grow larger, and any sedimentary textures and fossils that might have been present are destroyed. Physical Geology 2015-01-01T00:00:00Z As evaporation continues, the ooids continue building concentric layers of calcite as they roll around in gentle currents. An Introduction to Geology 2017-01-01T00:00:00Z As this calcite and other small sediments wash over the microbes, they get stuck on the microbes' sticky outer filaments. 6 Amazing Structures Built by Surprising Creatures 2018-05-07T04:00:00Z When polarized light passes through calcite, it splits into two beams. The Crystals That May Have Helped Vikings Navigate Northern Seas 2018-04-06T04:00:00Z But when readings were taken at intervals of 5 and 6 hours, calcite, a mineral well-known to the Vikings as “Icelandic spar,” performed slightly worse than the other two stones. Viking seafarers may have navigated with legendary crystals 2018-04-03T04:00:00Z Examples of minerals are feldspar, quartz, mica, halite, calcite, and amphibole. Physical Geology 2015-01-01T00:00:00Z The common mineral calcite has the chemical formula CaCO indicating the molecule consists of one calcium, one carbon, and three oxygen atoms. An Introduction to Geology 2017-01-01T00:00:00Z In a third cave, located in the far south, curtainlike calcite formations were decorated in shades of scarlet. Ancient Cave Paintings Clinch the Case for Neandertal Symbolism 2018-02-23T05:00:00Z Multiple samples from each painting yielded consistent results, and in several cases Hoffmann and his colleagues analyzed scrapings from increasing depths in the calcite layer. Europe’s first cave artists were Neandertals, newly dated paintings show 2018-02-22T05:00:00Z A novel determination of calcite dissolution kinetics in seawater. Meridional overturning circulation conveys fast acidification to the deep Atlantic Ocean 2018-02-11T05:00:00Z The largest stromatolites are around four inches across, but most are much smaller, and they have fine internal calcite layers. Stromatolites Defy Odds by A) Living B) on Land 2017-12-23T05:00:00Z In calcite, one carbon and three oxygen atoms are held together by covalent bonds to form a molecular ion, called carbonate, which has a negative charge. An Introduction to Geology 2017-01-01T00:00:00Z Rapid stepwise onset of Antarctic glaciation and deeper calcite compensation in the Pacific Ocean. Initiation and long-term instability of the East Antarctic Ice Sheet 2017-12-12T05:00:00Z Formed thousands of years ago by massive glaciers that ruptured the rock beneath, yellow calcite line the walls of the passage at times, adding pops of bright colour while icicle-shaped stalactites hang overhead. Amateur explorers discover vast underground passage beneath Montreal 2017-12-05T05:00:00Z Mucci, A. The solubility of calcite and aragonite in seawater at various salinities, temperatures, and one atmosphere total pressure. Meridional overturning circulation conveys fast acidification to the deep Atlantic Ocean 2018-02-11T05:00:00Z Inside was a brownish powder mingled with crystals of calcite and cowlesite. Moldy Rock Pulled from 2,500 Feet Underground 2017-09-23T04:00:00Z The two oppositely charged ions attract each other and combine to form the mineral calcite, CaCO . An Introduction to Geology 2017-01-01T00:00:00Z The occupation by bats likely dates back hundreds to thousands of years, evidenced by the sheer enormity of the bat bone deposits and the flowstone formations containing bat bones crystalized by calcite. Spanish Caves Reveal a Trove of Biological Treasures 2017-08-31T04:00:00Z Instead, Stinnesbeck’s team collected a fleck of the pelvis bone and surrounding stalagmite, which contains a mineral called calcite. Skeleton plundered from Mexican cave was one of the Americas’ oldest 2017-08-29T04:00:00Z Some parts of the underwater cave even preserved the footprints of ancient bears, crusted over in a film of calcite. Ice Age Predators Found Alongside Oldest Human in Americas 2017-08-25T04:00:00Z Their digestive system actually enriches the waste, grinding it up and adding calcite granules and friendly bacteria. She started composting. Who knew red wigglers and worm poop were so interesting? 2017-04-21T04:00:00Z The travertine terraces at Mammoth Hot Springs in Yellowstone Park are another example formed by calcite precipitation at the edges of the shallow spring-fed ponds. An Introduction to Geology 2017-01-01T00:00:00Z The Helgustadanama mine is famous for Icelandic spar, a type of transparent calcite which was historically used in scientific equipment. Concern over tourists taking crystals from Iceland mine - BBC News 2017-03-23T04:00:00Z The team then dated the rock using the relative levels of uranium and thorium isotopes in the calcite. Skeleton plundered from Mexican cave was one of the Americas’ oldest 2017-08-29T04:00:00Z This caused one particular nutrient needed for the formation of calcite and aragonite—calcium—to flood the oceans, which further fueled the evolution of skeletons, the team reports this month in Geology. How did animals get their skeletons? 2016-11-15T05:00:00Z He became fixated on a striking complex of dark-gray limestone blocks surrounded by whitish calcite, a shattered geometry reminiscent of a Futurist composition. Death Valley Is Alive 2016-11-06T04:00:00Z Marine invertebrates such as corals and clams precipitate aragonite or calcite for their shells and structures. An Introduction to Geology 2017-01-01T00:00:00Z Certain groups of clams and corals were decimated, as were the most important primary producers of the time, tiny planktonic foraminifera—one-celled organisms that create minute and wondrously elaborate shells of calcite. Did Oil Kill the Dinosaurs? 2016-07-14T04:00:00Z Eyewitness to Evolution writes that "The eyes of trilobites are composed of elongate prisms of clear calcite," and that they were sophisticated in these early days of life. Trilobites are the Legos of the Ordovician seas 2016-07-10T04:00:00Z Tests identified it as calcite, bearing the heavy carbon tracer that marked it as a product of carbonation. Underground injections turn carbon dioxide to stone 2016-06-10T04:00:00Z Specifically, the researchers turned it into carbonate minerals such as calcite and magnesite. Turning air into stone 2016-06-08T04:00:00Z If the acid drop effervesces or fizzes on the surface of the rock, the specimen is calcite. An Introduction to Geology 2017-01-01T00:00:00Z Early signs were encouraging: Among other things, a submerged pump that was used to obtain samples of the mixture as it spread underground stopped working after a while because it got gummed up by calcite. Iceland Carbon Dioxide Storage Project Locks Away Gas, and Fast 2016-06-09T04:00:00Z By analyzing the stalagmites as well as the calcite that grew on top of them, the researchers were able to date the site to about 176,500 years ago. Neanderthals were building complex cave structures much longer ago than we thought 2016-05-25T04:00:00Z Measurements of dissolved carbon in the groundwater suggested that more than 95% of the injected carbon had already been converted into calcite and other minerals. Underground injections turn carbon dioxide to stone 2016-06-10T04:00:00Z In the shell material, foraminiferal calcite, trace metals of similar size sometimes replace calcium; even trace anions can take the place of the carbonate ion. Harry Elderfield (1943-2016) : Nature : Nature Publishing Group 2016-05-17T04:00:00Z Later fluids filled in the fossil with white calcite minerals. An Introduction to Geology 2017-01-01T00:00:00Z The scientists found that about 95 percent of the carbon dioxide was converted into calcite. Iceland Carbon Dioxide Storage Project Locks Away Gas, and Fast 2016-06-09T04:00:00Z So the team dated various calcite deposits in the cave and used the assortment of animal remains to deduce that the human teeth were probably between 80,000 and 120,000 years old. Teeth from China reveal early human trek out of Africa 2015-10-13T04:00:00Z They knew that unlike sandstone, the basalt contains metals that react with CO2, forming carbonate minerals such as calcite—a process known as carbonation. Underground injections turn carbon dioxide to stone 2016-06-10T04:00:00Z They hope to date calcite deposits in the cave to establish the age of the remains, which could be more than 1 million years old. Crowdsourcing digs up an early human species 2015-09-09T04:00:00Z The line between the sediment and the later calcite is paleo-horizontal. An Introduction to Geology 2017-01-01T00:00:00Z A passageway led into a larger cavity, about 30 feet long and only a few feet wide, its walls and ceiling a bewilderment of calcite gnarls and jutting flowstone fingers. This Face Changes the Human Story. But How? 2015-09-10T04:00:00Z We weave along the narrow metal walkways; stalactites and stalagmites glimmer in the light, sparkling curtains of calcite hang down from above and the floor is awash with the bones of long-dead animals. Vast replica recreates prehistoric Chauvet cave - BBC News 2015-04-24T04:00:00Z Both times when it was hauled up for repairs it was covered in calcite. Burying a Mountain of CO2 2015-02-09T05:00:00Z A patina of calcite coated the fragment, and the researchers used radioactive uranium in the mineral to date the bone to about 55,000 years old. New Skull Could Be from Human Group that Interbred with Neandertals 2015-01-29T05:00:00Z In some cases such as with diatomaceous earth, sediment is deposited below the calcite compensation depth, a depth where calcite solubility increases. An Introduction to Geology 2017-01-01T00:00:00Z And when they hit calcite, they break it down into calcium, which combines with carbon from the air and re-forms as limestone. Can Geoengineering Save the Earth? The memorial was established in April 1996 with the placement of a limestone and calcite boulder. State crime victims memorial to get a facelift 2014-10-27T04:00:00Z Thin layers of calcite containing traces of uranium were deposited on the paintings as mineral-rich waters trickled down cave walls over thousands of years. Cave art and harpoon tips show African roots of our creative genius 2014-10-11T04:00:00Z Over the next 2 years, Aubert used a diamond saw blade to collect 19 samples of calcite popcorn from 14 paintings in seven caves within a 1-kilometer radius. Indonesian cave art may be world's oldest 2014-10-08T04:00:00Z Dissolved carbon is converted by marine organisms to calcite, which is stored in carbonate rocks for tens to hundreds of millions of years. An Introduction to Geology 2017-01-01T00:00:00Z The impact glass is completely replaced by minerals such as calcite and pyrite, but rare, space-linked elements such as platinum and ruthenium remain. Earth's Oldest and Biggest Crater Yields New Secrets 2014-04-29T22:00:00Z Some existing echinoderms, such as brittle stars, are covered in crystal calcite microlenses that are sensitive to light. Palaeontology: Ancient starfish spotted predators 2014-04-04T13:51:04.774Z Uranium decays into thorium at a specific rate and the team were able to calculate an accurate age of the painting by analysing levels of the two elements in the calcite. Cave art and harpoon tips show African roots of our creative genius 2014-10-11T04:00:00Z Trilobite eyes were unlike those of virtually any other known animal, the lenses built not of protein but of calcite crystals, lending the animals a “stony stare,” as Dr. Fortey put it. Basics: When Trilobites Ruled the World 2014-03-03T22:50:21Z Recall that hydrochloric acid reacts by effervescing with limestone rock made of calcite, which is calcium carbonate. An Introduction to Geology 2017-01-01T00:00:00Z Unfortunately, this is more sensitive to acidity than calcite is. The future of the oceans: Acid test 2013-11-21T16:03:53Z The species are called coralline algae because they deposit coral-like crusts of the mineral calcite on underwater rocks, coating the rocks with colorful pink splotches. Ancient Arctic Algae Record Climate Change in 'Tree Rings' 2013-11-18T23:45:00.493Z Mould, blackish film, green stains and calcite formed on the walls. Would you visit a fake tourist attraction? 2013-11-08T01:33:32Z But fairly late in trilobite evolution one group developed a different sort of eye, composed of a smaller number of larger, separated calcite lenses. Basics: When Trilobites Ruled the World 2014-03-03T22:50:21Z In mines where limestone is a waste rock of carbonate minerals like calcite or dolomite are present, their acid-neutralizing potential helps reduce the likelihood of generating ARD. An Introduction to Geology 2017-01-01T00:00:00Z Because the ratios of different isotopes, or forms, of oxygen within the calcite crystals vary with temperature, they record the conditions present as they grow inside the worms. Worm poo's window into past climate 2013-07-10T16:47:07Z To collect the crystalline crusts, divers chiseled off calcite shards from underwater rocks in the Labrador Sea offshore of Kingitok Island and in the Arctic Ocean near Nunavut, Canada. Ancient Arctic Algae Record Climate Change in 'Tree Rings' 2013-11-18T23:45:00.493Z Although coccolithophores export carbon in the form of organic matter and calcite to the sea floor, they also release CO in the calcification process. Pan genome of the phytoplankton Emiliania underpins its global distribution 2013-07-10T17:21:48.277Z In most trilobites, each compound orb held hundreds of tiny calcite lenses, arranged in a tightknit honeycomb pattern, like the eye of a fly. Basics: When Trilobites Ruled the World 2014-03-03T22:50:21Z This means that the calcite in the shell of a clam is not considered a mineral. An Introduction to Geology 2017-01-01T00:00:00Z Because the ratios of different isotopes, or forms, of oxygen within the calcite crystals vary with temperature they record the conditions present as they grow inside the worms. Worm poo's window into past climate 2013-07-10T16:47:07Z The squatter has a flexible organic wall, whereas the host shell is calcareous, meaning it contains calcite. Squatters of the microbial world: foram-in-a-foram 2013-06-12T23:45:00.353Z In one demonstration, they showed how small objects, such as paperclips and pins, could be made invisible beneath a cloak built from two calcite prisms joined together to make a pyramid. Animal invisibility cloak makes cat and fish vanish 2013-06-10T16:24:03Z The research group was conservative with the ages it reported last June, which put the earliest calcite at nearly 41,000 years old. Neanderthal culture: Old masters 2013-05-15T17:20:46.470Z This means that the calcite in the shell of a clam is not considered a mineral. An Introduction to Geology 2017-01-01T00:00:00Z Dr Ropars’s latest research, just published in the Proceedings of the Royal Society, used spectroscopy to confirm the stone’s composition as calcite. Navigation: Crystal gazing 2013-03-07T16:08:25Z Eggshells are mostly calcite crystals in a protein matrix, although even the mineral portion is laced with organic matter. Walking on Eggshells: Anatomy of a Science Story 2012-09-27T00:45:01.187Z Later, in 2011, Pendry teamed up with scientists at Birmingham University to show that invisibility cloaks could also be made from natural calcite crystals. Animal invisibility cloak makes cat and fish vanish 2013-06-10T16:24:03Z In the modern sea only aragonite and calcite are stable minerals and therefore can form directly by precipitaton from the water. The Mysterious Microbial Origin of Mountains 2012-06-21T16:45:02.283Z These minerals, such as calcite, amorphous silica, or oxides, may have a different composition than the sediment grains. An Introduction to Geology 2017-01-01T00:00:00Z Place a calcite crystal on a newspaper, and suddenly the image is doubled. Bright Idea: New "Tractor Beam" Proposal Relies on Light's Negative Radiation Pressure 2012-06-20T10:15:00.203Z In the process, the calcite incorporates small numbers of naturally occurring radioactive uranium atoms. Red dot becomes 'oldest cave art' 2012-06-15T00:32:09Z U-series dating takes advantage of the fact that calcite, the form of calcium carbonate in stalactites and stalagmites, contains trace amounts of radioactive uranium-238, which decays to form atomic elements including radioactive thorium-230. Did Neandertals Paint Early Cave Art? 2012-06-14T20:30:00Z Water seeping into caves leaves deposits of calcium carbonate, or calcite, as stalactites and stalagmites or simpler crusts over cave surfaces. New Dating Puts Cave Art in the Age of Neanderthals 2012-06-14T18:08:51Z Waterfalls downstream of springs often precipitate tufa as the turbulent water enhances the degassing of carbon dioxide, which makes calcite less soluble and causes it to precipitate. An Introduction to Geology 2017-01-01T00:00:00Z And is the calcite reminiscent of daggers or asparagus spears? If Facebook Delivers (Or Disappoints), Try Minerals 2012-05-18T18:19:21Z SEM analysis of the eggshell fragments reveals two equally thick shell layers formed of calcite crystals, as well as an absence of marked surface ornamentation. A drowned nesting colony of Late Cretaceous birds 2012-05-15T16:15:03.013Z Using a blade or an electric drill, the team took 50 small samples from calcite that directly overlay either paintings or engravings in 11 caves in northwest Spain. Did Neandertals Paint Early Cave Art? 2012-06-14T20:30:00Z The uranium-thorium method has now been made more sensitive, so that calcite samples of just 10 milligrams, about as small as a grain of rice, can do the job. New Dating Puts Cave Art in the Age of Neanderthals 2012-06-14T18:08:51Z Micrite, also known as microscopic calcite mud, is a very fine-grained limestone containing microfossils that can only be seen using a microscope. An Introduction to Geology 2017-01-01T00:00:00Z A variety of trap or basaltic rock, containing small cavities, occupied, wholly or in part, by nodules or geodes of different minerals, esp. agates, quartz, calcite, and the zeolites. Webster's Unabridged Dictionary 2012-03-24T02:00:23.513Z Given that this was confused with a theropod I’m guessing these were calcite eggs. A drowned nesting colony of Late Cretaceous birds 2012-05-15T16:15:03.013Z Because the calcite overlays the paintings, it must be younger than the art, and so yields minimum ages. Did Neandertals Paint Early Cave Art? 2012-06-14T20:30:00Z This name is also given to a white powdery variety of calcite. Webster's Unabridged Dictionary (2nd 100 Pages) 2012-03-24T02:00:19.387Z Turkey oilstone is a close-grained bluish stone 653 containing from 70 to 75% of silica in a state of very fine division, intimately blended with about 20 to 25% of calcite. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 6 "Home, Daniel" to "Hortensius, Quintus" 2012-03-15T02:00:32.250Z A mineral identical in composition with calcite or carbonate of lime, but differing from it in its crystalline form and some of its physical characters. Webster's Unabridged Dictionary 2012-03-24T02:00:23.513Z You can find any number of calcite veins running through the rocks here, where water dissolved the calcite from the limestone and redeposited it. M lange et Trois: A Trip Across Subduction Zone Madness 2012-03-07T22:15:00.213Z In a few cases, the team also dated calcite underneath artworks, thus creating a "sandwich" that generated maximum and minimum dates. Did Neandertals Paint Early Cave Art? 2012-06-14T20:30:00Z The bacteria enhanced the formation of calcite even when they were just lying around, not growing or multiplying. Genetically Engineered Bacteria Could Help Fight Climate Change 2012-02-26T17:00:00Z X-ray studies now show they are built from "bricks" of the crystal calcite, with a non-crystalline "mortar". Sea urchins inspire concrete idea 2012-02-15T01:57:53Z X-ray studies now show they are built from "bricks" of the crystal calcite, with a "mortar" of formless lime. Sea urchins inspire concrete idea 2012-02-15T01:57:53Z Large crystals, reaching 4 in. in length, have been found with calcite in veins traversing granite at Russell in St Lawrence county, New York. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 9 "Dagupan" to "David" 2012-02-11T03:03:39.807Z Regular intergrowths of crystals of totally different substances such as staurolite with cyanite, rutile with haematite, blende with chalcopyrite, calcite with sodium nitrate, are not uncommon. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7 "Crocoite" to "Cuba" 2012-01-22T03:00:24.397Z Better yet, more of it was in the crystalline calcite form, which is more stable—and likely to sequester CO over geological time—than amorphous CaCO. Genetically Engineered Bacteria Could Help Fight Climate Change 2012-02-26T17:00:00Z Ice′land-moss, a lichen found in Iceland, Norway, &c., valuable as a medicine and for food; Ice′land-spar, a transparent variety of calcite or calcium carbonate. Chambers's Twentieth Century Dictionary (part 2 of 4: E-M) 2012-01-11T03:00:23.770Z Sundry gold-reefs in Queensland, New South Wales, Victoria, and Bohemia are full of calcite. The Romance of Industry and Invention 2011-12-19T03:00:43.870Z In the first are found veins of calcite and quartz from half-an-inch to three inches thick, in which especially in the calcite the gold is visible mixed with iron and copper pyrites, galena and blende. The Inhabitants of the Philippines 2011-11-23T03:00:21.653Z In calcite, for instance, the figure has roughly the shape of a rounded rhombohedron with depressed faces and is symmetrical about three vertical planes. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7 "Crocoite" to "Cuba" 2012-01-22T03:00:24.397Z The stringers in the 8th stratum of stone, which fuse in the fire of the second order, were possibly calcite. De Re Metallica, Translated from the First Latin Edition of 1556 2011-11-16T03:00:21.977Z In the weathering of granite the quartz suffers little change; the felspar passes into dull cloudy, soft aggregates of kaolin, muscovite and secondary quartz, while chlorite, quartz and calcite replace the biotite, hornblende and augite. Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 3 "Gordon, Lord George" to "Grasses" 2011-11-13T03:00:13.177Z Iceland spar is a form of calcite that splits light into two beams. Viking navigation: Sunstruck 2011-11-02T18:18:03Z Physicists think Vikings could have used calcite crystals in a device like this to navigate on cloudy days. The Viking Sunstone Revealed? 2011-11-02T01:01:00Z This secondary twinning is often to be observed as a repeated lamination in the grains of calcite composing a crystalline limestone, or marble, which has been subjected to earth movements. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7 "Crocoite" to "Cuba" 2012-01-22T03:00:24.397Z The rauchstein of the modern section is distinguished by stringers of calcite, which give it at times a brecciated appearance. De Re Metallica, Translated from the First Latin Edition of 1556 2011-11-16T03:00:21.977Z In like manner he showed that all the forms of a given mineral, like fluor-spar or calcite, might be built up from the integrant molecules by skillfully placing together the primitive forms. Scientific Culture, and Other Essays Second Edition; with Additions 2011-09-17T02:00:31.747Z This is a large calcite crystal recovered from a vessel that went down off the coast of Alderney, in the Channel Islands, in Elizabethan times. Viking navigation: Sunstruck 2011-11-02T18:18:03Z Now a team of scientists claims that the sunstones could have been calcite crystals and that Vikings could have used them to get highly accurate compass readings even when the sun was hidden. The Viking Sunstone Revealed? 2011-11-02T01:01:00Z On rotating this crystal with respect to the instrument the maximum difference in the colours will be obtained when the vibration-directions in the crystal coincide with those in the calcite. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7 "Crocoite" to "Cuba" 2012-01-22T03:00:24.397Z Both gypsum and calcite, found in drywall and cement, irritate mucus membranes, like those in the eyes, nose and throat. What Was in the World Trade Center Plume? [Interactive] 2011-09-07T10:15:00.203Z It is often associated with blende and pyrites, and with calcite, fluorspar, quartz, barytes, chalybite and pearlspar as gangue minerals; in the upper oxidized parts of the deposits, cerussite and anglesite occur as alteration products. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 4 "G" to "Gaskell, Elizabeth" 2011-08-24T02:00:20.690Z The mineral calcite, which sometimes is used as a waveplate, is birefringent. Mantis Shrimp Eye Could Improve HD CDs, DVDs 2011-06-27T15:22:00Z To see if calcite is accurate enough for navigation, a team led by Guy Ropars, a physicist at the University of Rennes 1 in France, built a sunstone. The Viking Sunstone Revealed? 2011-11-02T01:01:00Z Further, by stacking together a number of small rhombohedra of uniform size he was able, as had been previously done by J. G. Gahn in 1773, to reconstruct the various forms of calcite crystals. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7 "Crocoite" to "Cuba" 2012-01-22T03:00:24.397Z Depending on the angle at which the photon traverses the calcite, it would slightly skew the photon's polarization from the 50-50 mixture. Quantum Mechanics Gets Weirdly Less Weird 2011-06-02T19:00:00Z A passage to the right brings you to the Dropping Cave, with walls and ceiling of dark blue limestone streaked with white calcite, and water dropping everywhere from the roof. Among the Canadian Alps 2011-05-30T02:00:16.600Z This print viewed through a calcite lens appears as doubled and slightly offset letters. Mantis Shrimp Eye Could Improve HD CDs, DVDs 2011-06-27T15:22:00Z It has a property called birefringence: Light passing through calcite is split along two paths, forming a double image on the far side. The Viking Sunstone Revealed? 2011-11-02T01:01:00Z Inclusions of other minerals are specially frequent and conspicuous in crystals of quartz, and crystals of calcite may contain as much as 60% of included sand. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7 "Crocoite" to "Cuba" 2012-01-22T03:00:24.397Z One of the projected impacts of ocean acidification is a decline in the availability of carbonate, which many sea creatures extract to form aragonite and calcite. Driving needs 2011-05-27T14:03:39Z The shell of Endothyra, a form only known to us by its abundance in Carboniferous and Triassic strata, is largely composed of calcite and is sometimes perforated. Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 6 "Foraminifera" to "Fox, Edward" 2011-04-22T02:00:08.637Z Typically, waveplates are made from minerals such as quartz, calcite or birefringent polymers. Mantis Shrimp Eye Could Improve HD CDs, DVDs 2011-06-27T15:22:00Z Fluor-spar has a hardness of 4, so that it is scratched by a knife, though not so readily as calcite. Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 5 "Fleury, Claude" to "Foraker" 2011-04-03T02:00:20.883Z The emerald occurs in nests of calcite in a black bituminous limestone containing ammonites of Lower Cretaceous age. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z They adopted calcite prisms, a type of naturally occurring crystal, to build carpet cloaks. Invisibility Cloaks Hit the Big Time 2011-02-02T16:52:00Z But the principle in calcite is different altogether. Crystal-clear idea for cloaking 2011-02-01T18:56:19Z Image Right: The phenomenon of double refraction in calcite. Invisibility: After several years of research, it's just gotten weirder 2011-01-11T18:45:11.203Z Using real-time microscopic examinations, including calcium imaging and photosynthetic analysis, coupled with molecular genetics, the trio examined the cyanobacteria's invasion of calcite chips and the physiological mechanisms at play. Mystery Dissolves With Calcium Pump Discovery 2010-12-01T17:13:00Z They dated the layers of the mineral calcite, which were deposited by the seawater in rings on the cave walls, as on a bathtub. 2010-02-11T23:15:00Z Aragonite passes into calcite in the course of geological time, but is important as the mineral precipitated to form the oolitic limestones of warm seas, and from being the material of most molluscan shells. The New Gresham Encyclopedia. Vol. 1 Part 2 Amiel to Atrauli From a solution of calcium carbonate in water containing carbon dioxide crystals of calcite are deposited at the ordinary temperature, but from a warm solution aragonite crystallizes out. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 3 "Apollodorus" to "Aral" A ring-shaped plate of calcite, secreted by the ectoderm, is then formed, lying between the embryo and the surface of attachment. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 2 "Anjar" to "Apollo" This dripstone, as the material of the formation is termed, began as soft carbonate of lime; it hardens into gypsum or, sometimes, alabaster, or calcite. Unexplored! Chalybite crystallizes in the rhombohedral system and is isomorphous with calcite; like this it possesses perfect cleavages parallel to the faces of the primitive rhombohedron, the angles between which are 73� 0′. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" Colourless crystals, of great beauty, occur in association with calcite and native sulphur in the sulphur deposits of Sicily, as at Girgenti. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 5 "Cat" to "Celt" The mineral is colourless, white or yellowish, transparent or translucent, has a vitreous lustre, and, in fact, is not unlike calcite in general appearance. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 3 "Apollodorus" to "Aral" The distribution of the calcite may be rendered more clear by using ferric chloride solution. Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 6 "Dodwell" to "Drama" The other minerals found in the concentrates are pebbles and fragments of pyrope, zircon, cyanite, chrome-diopside, enstatite, a green pyroxene, mica, ilmenite, magnetite, chromite, hornblende, olivine, barytes, calcite and pyrites. Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 4 "Diameter" to "Dinarchus" The reason that calcite is hard to find in rocks is that percolating water, charged with acids, is constantly stealing it, and carrying it away into the ocean. Earth and Sky Every Child Should Know Easy studies of the earth and the stars for any time and place When split open they prove to be traversed by a network of cracks, which are usually filled with calcite and other minerals. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 7 "Columbus" to "Condottiere" The divisional planes often contain small films of other minerals, the commonest being calcite, gypsum and iron pyrites, but in some cases zeolitic minerals and galena have been observed. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 5 "Clervaux" to "Cockade" Magnesian limestones, which contain both dolomite and calcite, may be etched by exposing polished surfaces for a brief time to cold weak acid; the calcite is removed, leaving small pits or depressions. Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 6 "Dodwell" to "Drama" They are principally finely divided quartz, epidote, zoisite, rutile, limonite, calcite, pyrites, and very small particles of these are rarely absent from natural clays. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 4 "Cincinnatus" to "Cleruchy" They are made of the elements calcium, carbon, and oxygen, yet the different members of this calcite group differ widely in composition and appearance. Earth and Sky Every Child Should Know Easy studies of the earth and the stars for any time and place In the first class 74 are included sulphur and ammonium nitrate; monotropy is exhibited by aragonite and calcite. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" Cerium looks like iron, having both its color and lustre, but is heavier, and has the hardness of calcite. The Galaxy, Volume 23, No. 2, February, 1877 This is decomposed, leaving a yellow stain of ferric hydrate where the calcite occurred. Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 6 "Dodwell" to "Drama" But he was glad of the prospect of renewed hard work upon his claim, of promising toil to expose further the great silver-bearing veins of calcite that wound their way through the harder rock. The Peace of Roaring River The skeletons and shells of animals are made of calcite, a common mineral formed by the uniting of carbon, oxygen, and calcium. Earth and Sky Every Child Should Know Easy studies of the earth and the stars for any time and place Calcium carbonate may crystallize in either of two forms, calcite or aragonite. A Text-Book of Precious Stones for Jewelers and the Gem-Loving Public These are commonly quartz, calcite, or iron oxide, of no especial value, but locally they include commercially valuable minerals containing gold, copper, silver, lead, zinc, and many other mineral products. The Economic Aspect of Geology They are composed of fibrous radiate calcite crystals, which by some kind of concretionary action have segregated from the dolomitic material and grouped themselves together in this way. Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 6 "Dodwell" to "Drama" Basaltic lavas are frequently spongy or pumiceous, especially near their surfaces; and, in course of time, the steam cavities become filled with secondary minerals such as calcite, chlorite and zeolites. Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 3 "Banks" to "Bassoon" "Hard" water has filtered through rocks containing calcite, and absorbed particles of this mineral. Earth and Sky Every Child Should Know Easy studies of the earth and the stars for any time and place Their bright light showed the night reticulated with thin lines of smoke, like veins of calcite in a canopy of black marble. Waiting for Daylight Some of the dissolved substances of weathering, such as calcite, quartz, and iron oxide, are carried down and deposited in openings of the rocks, where they act as cements. The Economic Aspect of Geology Many limestones are rich in aragonite, but this in course of time tends to recrystallize as calcite. Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 6 "Dodwell" to "Drama" The matrix contains lime as is seen in the large amount of calcite that exists. The Incomparable 29th and the "River Clyde" Joined with calcium it forms the mineral calcite, or carbonate of lime. Earth and Sky Every Child Should Know Easy studies of the earth and the stars for any time and place It was not common carbonate of lime, for the crystals were rhombohedral and did not show the cleavage of calcite. The Voyage of the Vega round Asia and Europe, Volume I and Volume II Furthermore, the quartz gangue near the igneous rock is likely to contain minerals characteristic of hot solutions, while farther away such minerals as dolomite and calcite appear in the gangue, suggestive of cooler conditions. The Economic Aspect of Geology Dolomite also being denser than calcite may be supposed to replace it more readily when pressure is increased. Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 6 "Dodwell" to "Drama" One of the crystals that he thought was quartz turned out to be calcite, and one of the ones that he was sure could be nothing but calcite was actually potassium nitrate. All Day September Those stones which show electricity on the application of pressure are such as the fluorspar, calcite, and topaz. The Chemistry, Properties and Tests of Precious Stones Transparent calcite, a mineral commonly called "Iceland spar," is found, one mine of which furnishes an excellent quality. Wealth of the World's Waste Places and Oceania The primary ores consist of pyrite, chalcopyrite, and other sulphides, with large amounts of jaspery quartz and some calcite and dolomite. The Economic Aspect of Geology That is calcite, and this rock is a black limestone; all the indications are, therefore, in favour of this being a genuine emerald mine, which we can work, if we choose, on our return journey. In Search of El Dorado I seemed to look up and so clearly visualized those icicles hanging like stalactites from a flat-roofed cave, in white calcite. The Book of the Damned It occurs in a number of localities as magnesite, which is usually amorphous, but sometimes forms pure crystals resembling calcite. An Elementary Study of Chemistry Crystals of calcite are extremely varied in form, but, as a rule, they may be referred to four distinct habits, namely: rhombohedral, prismatic, scalenohedral and tabular. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" The large fluorspar deposits of Illinois and Kentucky contain fluorite with calcite, barite, and metallic sulphides, in wide veins filling fissures in limestones and sandstones and replacing the fissure walls. The Economic Aspect of Geology Cell life was powerless before the vanquishing crystals of the infiltrating calcite. Some Winter Days in Iowa Additional minerals found in the coarse schists are calcite, ilmenite, skeleton oblivine, biotite, and hematite. History and Comprehensive Description of Loudoun County, Virginia Marble when pure is made up of minute calcite crystals. An Elementary Study of Chemistry In addition to the varieties of calcite noted above, some others, depending on the state of aggregation of the material, are distinguished. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" They are variously associated with a gangue of dolomite, calcite, quartz, iron pyrite, barite, and chert. The Economic Aspect of Geology Planes or crystal ghosts, sometimes with pyrite crystals, marking stages of growth in the calcite crystals, are often distinguishable. Cave Regions of the Ozarks and Black Hills From here, for a long distance, the road was a hard, steep climb, over limestone in great variety—solid limestone, tufaceous stuff, concretionary coatings, satin spar, and calcite crystals. In Indian Mexico (1908) In the case of thin plates of calcite, a solid cementing substance of sufficiently high refractive power was not available, and a fluid medium was therefore employed. Scientific American Supplement, No. 441, June 14, 1884. Veins and cavities in limestones are usually lined with crystals of calcite. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" The gold, in particles hardly visible to the eye, is in a sandy matrix and is associated with chloritoid, sericite, calcite, graphite, and other minerals. The Economic Aspect of Geology It is composed of a series of connected calcite bowls whose beautifully fluted rims are of regular and uniform height, and all are equally filled with clear, still water. Cave Regions of the Ozarks and Black Hills Some marble tables are also in this room, placed here to exhibit the beauties of various calcites. How to See the British Museum in Four Visits It crystallizes in similar form to calcite, and in both cases thin plates obtained by cleavage may be used. Scientific American Supplement, No. 441, June 14, 1884. Only very occasionally has calcite from any locality other than Iceland been used for the construction of a Nicol's prism. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" Native silver and various silver sulphides, arsenides, and antimonides are associated with minerals of cobalt, nickel, bismuth, lead, and zinc, in a gangue of calcite and some quartz. The Economic Aspect of Geology This calcium carbonate was slowly deposited in crystalline form, so that in time the cracks were filled and the crushed rock firmly cemented with calcite seams. Cave Regions of the Ozarks and Black Hills The forty-sixth case is also covered with calcites, including the reastone, the limestone incrusted upon a human skull, found in the Tiber at Rome. How to See the British Museum in Four Visits The bent and metamorphosed condition of the calcite shows the shearing and crushing which the rock has undergone. The Long Labrador Trail It is rhombohedral in crystallization and isomorphous with calcite and chalybite. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" The cementing or gangue materials are chiefly calcite and quartz, in variable proportions. The Economic Aspect of Geology Here all was calcite crystal heavily massed in various forms, and a harmony of blue and brown, with half a dozen round, unbroken, perfect geodes hanging from the ceiling like oriole nests. Cave Regions of the Ozarks and Black Hills There are the varieties of three minerals, which are very commonly met with in greater or less abundance in mineralogical trips: they are of calcite, steatite, and quartz. Scientific American Supplement, No. 344, August 5, 1882 The results of shearing and pressure are very prominent and bring out the foliation, even in the calcite. The Long Labrador Trail The latter mode of origin is suggested by the frequent occurrence of calamine pseudomorphous after calcite, that is, having the form of calcite crystals. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" In these occurrences the tungsten mineral is almost invariably scheelite, and is associated with calcite, garnet, pyroxene, and other silicates. The Economic Aspect of Geology This chamber proved to be a little gem; small but high, and beautifully adorned with calcite crystal. Cave Regions of the Ozarks and Black Hills The next mineral abundant in so many forms is quartz, and is not so readily distinguished as calcite. Scientific American Supplement, No. 344, August 5, 1882 A white rock having a peculiar mottled appearance due to the inclusions of decomposing biotite which project from the surrounding mass of calcite. The Long Labrador Trail The cleavage is of great help in distinguishing calcite from other minerals of similar appearance. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" Their occurrence here is in calcite veins in a bituminous limestone, but little seems to be known of their origin. The Economic Aspect of Geology The floor is covered with a light yellow crust of calcite crystal, sufficiently strong to bear the weight of a limited number of guests without much fracture. Cave Regions of the Ozarks and Black Hills Laumonite occurs in very small quantities on calcite or apopholite, and can hardly be expected to be found on the trip; but as it might be found, I will detail some of its characteristics. Scientific American Supplement, No. 344, August 5, 1882 On observing it under polarized light the calcareous substance is discovered to be everywhere crystallized, and this suggests the question whether the carbonate has here taken the form of aragonite or of calcite. Scientific American Supplement, No. 286, June 25, 1881 Localities at which beautifully crystallized specimens of calcite are found are extremely numerous. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" Light is polarized in several ways—by reflection, by transmission, but most commonly through what I have here, a prism of calcite, or Iceland spar, commonly called a Nicol prism. The Treasure-Train A wonderful effect is produced by the white calcite crystal spread in unequal thickness over the dark surface of the encrusted rocks. Cave Regions of the Ozarks and Black Hills Apopholite is distinguished from calcite, as noticed under that species, and from the others by its form, difficult fusibility, and part solubility. Scientific American Supplement, No. 344, August 5, 1882 How Minerals Got Their Names Names of most minerals end in "ite"—apatite, calcite, dolomite, fluorite. Let's Collect Rocks and Shells Aragonite is the least stable form; crystals have been found altered to calcite. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" The most common petrifying materials are calcite, silica, and pyrite. The Elements of Geology In all cases the original box work has been in thin sheets of calcite, and the heavy varieties are due to later deposits of calcite and aragonite crystals or, pop corn. Cave Regions of the Ozarks and Black Hills Datholite is also very characteristic in appearance, and can only be confounded with some forms of calcite occurring near it. Scientific American Supplement, No. 344, August 5, 1882 The other salts of lime, including its carbonate or calcite, although often met with, are invariably products of secondary chemical action. The Student's Elements of Geology In the form of stalactites calcite is of extremely common occurrence. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" Limestones, however, are metamorphosed by pressure into marble, the grains of carbonate of lime recrystallizing freely to interlocking crystals of calcite. The Elements of Geology The thin sheet of yellow calcite crystal thus broken was the same as that seen in great abundance in the now perfectly dry eighth level. Cave Regions of the Ozarks and Black Hills The fracture being at perfect right angles, distinguishes it from calcite. Scientific American Supplement, No. 344, August 5, 1882 Here we find caverns that for variety and beauty of their calcite formations excel many if not all caverns of the same kind in the world. See America First The modes of occurrence of calcite are very varied. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" It occurs embedded in or incrusting the trap, and also with calcite and apopholite. Scientific American Supplement, No. 344, August 5, 1882 The ores of calcite first mentioned are very conspicuous, they being white in the dense black rock. Scientific American Supplement, No. 344, August 5, 1882 Another form of calcite which is to be sparingly found is what is called dogtooth spar, having the form shown in Fig. Scientific American Supplement, No. 344, August 5, 1882 Where the most minerals occur in the chlorite is when plenty of veins of calcite are in its vicinity, and its edges near the trap are dry and crumbly. Scientific American Supplement, No. 344, August 5, 1882 In the animal kingdom it occurs as both calcite and aragonite in the tests of the foraminifera, echinoderms, brachiopoda, and mollusca; also in the skeletons of sponges and corals. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" It is readily mistaken for calcite by the miners and those unskilled in mineralogy, but a drop of acid will quickly show the difference. Scientific American Supplement, No. 344, August 5, 1882 |
| 随便看 |
|
英语例句辞典收录了117811条英语例句在线翻译词条，基本涵盖了全部常用单词及词组的例句翻译及用法，是英语学习的有利工具。