pitchstone

• 一种深色玻璃质的火山岩，成分与花岗岩相似，外观类似树脂。

A dark, glassy volcanic rock of granitic composition, resembling pitch in appearance.

1. Dark acid granitic glassC2formalscientific

   A natural volcanic glass with a dark, resinous or pitch-like luster, typically composed of acidic magma.

   深色酸性花岗玻璃

   • The geologist identified the sample as pitchstone due to its characteristic dark, glossy surface.
   • Pitchstone is often found in volcanic regions where acidic lava cooled rapidly.
   • Unlike obsidian, pitchstone has a higher water content and a duller, more resinous appearance.