igneous

Obsidian

Volcanic glass (SiO2 - Silicon Dioxide with impurities)

Hardness: 5–5.5; Color: Jet black (can be dark green or brown); Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.4

Hardness: 5–5
Color: Jet black (can be dark green or brown)
Luster: Vitreous/Glassy

Identified April 5, 2026More igneous →

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Physical properties

Hardness: 5–5.5; Color: Jet black (can be dark green or brown); Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.4

Formation & geological history

Formed from the rapid cooling of silica-rich (felsic) lava, which prevents crystal growth. It is primarily found in Cenozoic era volcanic regions.

Uses & applications

Historically used for arrowheads and blades; modernly used for high-end surgical scalpels, decorative ornaments, gemstone jewelry, and metaphysical collecting.

Geological facts

Because it is a glass and not a true mineral, it is technically a 'mineraloid.' It produces a cutting edge many times sharper than high-quality steel scalpels.

Field identification & locations

Identify by its characteristic shell-like (conchoidal) fracture lines and extremely sharp edges. Commonly found in volcanic fields such as those in Iceland, Mexico, or the Western USA.

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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)

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Blue Apatite

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

mineral

Magnetite

Magnetite (Fe3O4)

mineral