Simple Lithology

glassy igneous rock

definition Igneous rock that consists of greater than 80 percent massive glass. more like this
history note Change percent criteria from 90 to 80 percent for version 2009. more like this
note Note that this category is used for massive glassy rocks. Much of the pyroclastic material in a pyroclastic rock may be composed of glass, but the rock is named based on its fragmental nature. more like this
source This vocabulary more like this
broader glass rich igneous rock
narrower glassy igneous rock
in scheme simplelithology
is primary topic of glassy igneous rock