igneous

Black Obsidian

Obsidian (Volcanic Glass, SiO2 + impurities)

Hardness: 5-5.5 (Mohs scale), Color: Jet black, Luster: Vitreous/Glassy, Crystal structure: Amorphous (none), Cleavage: None (conchoidal fracture), Specific gravity: 2.35-2.6

Hardness: 5-5

Identified May 25, 2026More igneous →

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Physical properties

Hardness: 5-5.5 (Mohs scale), Color: Jet black, Luster: Vitreous/Glassy, Crystal structure: Amorphous (none), Cleavage: None (conchoidal fracture), Specific gravity: 2.35-2.6

Formation & geological history

Formed when felsic lava extruded from a volcano cools rapidly with minimal crystal growth. It is primarily found in Holocene and Pleistocene volcanic fields as it devitrifies over time.

Uses & applications

Historically used for blades, arrowheads, and scrapers. Modern uses include surgical scalpels, ornamental jewelry, carvings, and metaphysical collecting.

Geological facts

Obsidian is technically a natural glass rather than a true mineral because it lacks a crystalline structure. It can be sharper than high-quality steel scalpels.

Field identification & locations

Identified by its deep black color, lack of grain, and distinctive shell-like (conchoidal) fracture lines. Found in volcanic regions like the American West (Glass Buttes), Mexico, and Iceland.

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

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Dark Igneous Rock (Likely Basalt or Diabase)

Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

Igneous

Magnetite

Iron(II,III) oxide (Fe3O4)

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Blue Apatite

Apatite (Group), Ca5(PO4)3(F,Cl,OH)

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Magnetite

Magnetite (Fe3O4)

mineral