It is shown that expansible ettringite forms in the topochemical reaction,and crystallizes in-situ on the surface of unhydrated aluminate minerals and orients radially.

发现能够产生膨胀的钙矾石是由局部化学反应所生成；它们在未水化的铝酸盐矿物表面原地结晶，呈放射状生长。