| 单词 | pegmatite |
| 例句 | A rock that chiefly consists of pegmatitic texture is known as a pegmatite. An Introduction to Geology 2017-01-01T00:00:00Z The pegmatites in the Spruce Pine Mineral District, an area about 25 miles long and 10 miles wide, were formed hundreds of millions of years ago under intense heat and pressure. The special ingredient of those brilliant white sand traps at the Masters 2020-11-11T05:00:00Z Piedmont Lithium says it would be the nation’s only hard-rock mine, extracting lithium from a mineral, spodumene, that is found in rock called pegmatite. Demand for lithium could revive North Carolina mines 2019-04-06T04:00:00Z From a builder’s point of view, schist and pegmatite are a blessing as well as a curse. Excavation for Railyard Project Reveals a Hidden Piece of New York City 2014-07-02T04:00:00Z The aplites, pegmatites, graphic granites and muscovite granites are usually richest in silica, while with increase of biotite and hornblende, augite and enstatite the analyses show the presence of more magnesia, iron and lime. Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 3 "Gordon, Lord George" to "Grasses" 2011-11-13T03:00:13.177Z Emerald has been worked in a vein of pegmatite, piercing slaty rocks, near Emmaville, in New South Wales. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z The granite, which is intruded through the Eocene beds, is associated with a pegmatite containing tourmaline and cassiterite. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 2 "Ehud" to "Electroscope" 2011-01-29T03:00:23.777Z Chrysoberyl is known as a constituent of certain kinds of granite, pegmatite and gneiss. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 3 "Chitral" to "Cincinnati" The resulting folds are easy to see, because molten pegmatite penetrated the voids. Excavation for Railyard Project Reveals a Hidden Piece of New York City 2014-07-02T04:00:00Z They are not themselves igneous rocks and they do not constitute pegmatites, but they often grade into pegmatites and belong to the same general stage in the sequence of events. The Economic Aspect of Geology Autunite is usually found with pitchblende and other uranium minerals, or with ores of silver, tin and iron; it sometimes coats joint-planes in gneiss and pegmatite. Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 1 "Austria, Lower" to "Bacon" The majority of these bowlders have been derived from the immediate vicinity, but many consisting of a coarse pegmatite carrying considerable quantities of ilmenite were observed. The Long Labrador Trail In the bed of the river, I still found pebbles of pegmatite, granite, quartz, and basalt; indicating that a country of varied character was before us. Journal of an Overland Expedition in Australia : from Moreton Bay to Port Essington, a distance of upwards of 3000 miles, during the years 1844-1845 At Bahia the pegmatite and gneiss in beds had the same direction, as observed by Humboldt, prevailing over Columbia, distant 1300 miles—is it not wonderful? Life and Letters of Charles Darwin — Volume 1 In the United States rubies have been found in pegmatites in North Carolina, but these gems are of little commercial importance. The Economic Aspect of Geology The pegmatites thus afford a connecting link between ores of direct igneous sources and ores formed as "igneous after-effects," which are discussed in the next paragraph. The Economic Aspect of Geology Aplites are fine-grained acid igneous rocks of somewhat the same composition as the pegmatites and often show the same general relations to ores. The Economic Aspect of Geology The veins which traversed these rocks were all of quartz, which, within the pegmatite, enlarged into big masses and hills, particularly where basaltic rock was near. Journal of an Overland Expedition in Australia : from Moreton Bay to Port Essington, a distance of upwards of 3000 miles, during the years 1844-1845 The zirconium silicate, zircon, is a fairly common accessory constituent of granitic rocks and pegmatite veins. The Economic Aspect of Geology They are sometimes designated by the general term "igneous after-effects"—a term also applied in some cases to pegmatites. The Economic Aspect of Geology Some of the graphite also occurs in pegmatite intrusives and adjacent wall rocks. The Economic Aspect of Geology This inorganic graphite in pegmatite veins resembles Ceylon graphite, in breaking into large lumps and chips, but supplies are very limited. The Economic Aspect of Geology The country was very mountainous; granitic and pegmatite ranges bounded the valley on both sides. Journal of an Overland Expedition in Australia : from Moreton Bay to Port Essington, a distance of upwards of 3000 miles, during the years 1844-1845 In still rarer cases they are in pegmatites. The Economic Aspect of Geology The deep-zone minerals are not unlike the pegmatite minerals in their grouping and associations. The Economic Aspect of Geology They are not found in magmatic segregations, in pegmatites, nor in veins which have been formed at great depths and under very high temperatures. The Economic Aspect of Geology Yellowish-brown crystals of monazite have been found scattered through granites, gneisses, and pegmatites, but in quantities ordinarily too small to warrant mining. The Economic Aspect of Geology The bed of it had again become sandy, with small pebbles of pegmatite and quartz. Journal of an Overland Expedition in Australia : from Moreton Bay to Port Essington, a distance of upwards of 3000 miles, during the years 1844-1845 These minerals are formed mainly under high temperatures, either during the original solidification of igneous rocks, or as constituents of the pegmatites which follow the crystallization of the main igneous masses. The Economic Aspect of Geology Certain special varieties of igneous rocks, known as pegmatites, carry coarsely crystallized mica and feldspar of commercial value, as well as a considerable variety of precious gems and other commercial minerals. The Economic Aspect of Geology Barite itself is not found as an original constituent of igneous rocks or pegmatites, but is apparently always formed by deposition from aqueous solutions. The Economic Aspect of Geology In general the principal gem minerals, except pearl and turquoise, occur as original constituents in igneous intrusives, usually of a pegmatite or peridotite nature. The Economic Aspect of Geology Granite and pegmatite were round some lagoons near the creek from the southward. Journal of an Overland Expedition in Australia : from Moreton Bay to Port Essington, a distance of upwards of 3000 miles, during the years 1844-1845 In one of the creeks I observed pegmatite; pebbles of talc-schiste and of white quartz covered the bed of the river. Journal of an Overland Expedition in Australia : from Moreton Bay to Port Essington, a distance of upwards of 3000 miles, during the years 1844-1845 |
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