Explanation

Acid glass extrusive rock with turpentine luster. Its chemical composition is similar to that of perlite and obsidian, but its water content (>6%) is high. It is a kind of rock almost entirely composed of glass. It is often black, gray, light green, brown, yellow white, etc. Rosin luster and shell like fractures. It is the raw material for manufacturing expanded perlite, and its products are widely used in construction, chemical industry, petroleum, metallurgy, electric power, thermal insulation, sound insulation, soil improvement and other fields. China is rich in pitchstone resources, which are mostly associated with perlite and obsidian.

Classification