Leavy notes these varieties usually come from countries in Central America, like Mexico or Guatemala, where there's a lot of volcanic activity. Obsidian breaks with a conchoidal fracture that seems to ripple. Although obsidian is similar to glass when broken, it tends to be harder due to its content of silica (SiO2). It is brittle, hard, and relatively firm to slightly soft. But there's also silver sheen and gold sheen obsidian, which have a silver or gold tint, respectively. Obsidian is typically dark-colored with a vitreous or glassy luster and has a Mohs hardness of 7 to 8.
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