珍珠岩是酸性岩浆喷出而成的玻璃质熔岩,是酸性喷出岩的一种特殊变种。在新鲜断口上可见到珍珠光泽,其特点是在酸性火山玻璃基质中含有棕黑到褐色的球粒,一般为球形,也有的呈豆状,直径为2—8毫米;有时球粒连在一起成肾状或透镜状结合体,也有的成条带状球粒夹层。基质有时具流纹构造,或者像洋葱皮似的同心裂纹,形成珍珠构造。它是生产膨胀珍珠岩的原料。 Perlite is a vitreous lava sprayed from acidic magma and is a special variant of acid-expelled rock. Pearl luster can be seen on the fresh fracture, which is characterized by containing brown to brown pellets in acidic volcanic glass matrix, usually spherical, and some bean-shaped, 2-8 mm in diameter; sometimes the pellets are connected together Renal or lenticular combination, but also some ribbon-like sandwich. The matrix sometimes has a flow pattern, or concentric cracks like onion skin, forming a pearl structure. It is the raw material for producing expanded perlite.