Liparite

Liparite, Rhyolite, or Quartz-Trachyte, a comparatively modern acidic lava, varying considerably in texture, colour, and composition, but having a generally glassy ground-mass containing crystals of sanidine and quartz with various accessory minerals, and named from its extensive occurrence in the Lipari Islands. It contains about 76 per cent. of silica, 13 of alumina, 5 of soda, 4 of potash, and more than 1J of iron-oxide; and its specific gravity is 2-5 to 2-6. It occurs extensively in Hungary, Iceland, and the western United States. Its glassy condition is obsidian (q.v.).