火山玻璃岩是黑曜岩、松脂岩和珍珠岩等岩石的统称。其组成物质的80-100%为火山玻璃,通常是流纹质和英安质岩浆(酸性岩浆,因此类熔岩粘度大,温度低,在快速冷却时最容易形成玻璃质)在地表快速冷凝的产物。三者主要的区别是含水量不同,其中黑曜岩含水量很低(<1%),松脂岩含水量很高(一般为4-10%),珍珠岩居中(一般为3-4%)。
岩架上覆盖了厚厚的火山灰烬,其间点缀着火山玻璃珠和被称之为火山毛(Pele ' s hair)的熔岩细线。
The ledge was covered with heavy ash, called tephra, and speckled with droplets of volcanic glass and delicate lava threads known as Pele's hair.
火山岩包括黑曜岩火山玻璃。
水下喷发火山岩典型标志为珍珠岩、玻璃质结构、枕状构造、纹层状凝灰岩和膨润土。
Typical features of subaqueous volcanic rocks include perlite with glassy structure and pillow structure, lamellar tuff, bentonite.
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