In the pre-Colombian civilizations, the obsidian served to make masks, diverse objects, arrowheads and even razors. The Mayas extracted it from careers(quarries) of Joya, in around thirty kilometers from Guatemala City; the Incas, probably quarries of Guama
The obsidian is a natural glass ( glassy rock), formed from an acid lava of type rhyolite which cooled too quickly to crystallize. It is thus amorphous, without cleavage. The break is conchoïdale.
This gemstone is generally black, sometimes brown or grey and, more rarely, red, blue or green. It presents a uniform color, associated with stripes or flecks.
Certain inclusions give metallic glints, bubbles or internal crystals (sphérolites of feldspars) in white spots which produce an effect of "snowflakes" either the colored iridescences.
The obsidian is used a lot lithothérapie there.
