igneous and mineral
Black Obsidian and Hematite
Volcanic Glass (SiO2) and Hematite (Fe2O3)
Obsidian: Hardness 5-5.5, concoidal fracture, vitreous luster. Hematite: Hardness 5.5-6.5, metallic luster, reddish-streak.
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Physical properties
Obsidian: Hardness 5-5.5, concoidal fracture, vitreous luster. Hematite: Hardness 5.5-6.5, metallic luster, reddish-streak.
Formation & geological history
Obsidian forms from rapidly cooling extrusive volcanic lava. Hematite is a common iron-oxide mineral formed in hydrothermal veins or sedimentary environments.
Uses & applications
Jewelry, meditation tools, ornamental beads, and historical cutting tools.
Geological facts
Obsidian was prized by ancient civilizations for making surgical-grade blades due to its ability to hold an edge thinner than steel.
Field identification & locations
Identify Obsidian by its pitch-black color and glass-like surface. Identify Hematite by its metallic silver sheen and heavy weight for its size.
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