Cryptocrystal

A cryptocrystal is a rock whose texture is so finely crystalline?that is, made up of such minute crystals?that its crystalline nature is only vaguely revealed even in a thin section by transmitted polarized light. Among the sedimentary rocks, chert and flint are cryptocrystalline. Also a form of diamond, known as carbonado, is cryptocyrstalline. Lava flows, especially of the acidic type such as felsites and rhyolites, may have a cryptocrystalline ground mass as distinguished from pure obsidian (acidic) or tachylite (basic), which are natural rock glasses.

Related Topics:
Rock - Crystal - Polarized light - Sedimentary rock - Chert - Flint - Carbonado - Lava - Acid - Felsite - Rhyolite - Obsidian - Tachylite - Glass

~ ~ ~ ~ ~ ~ ~ ~ ~ ~