igneous

Olivine (Peridotite)

Magnesium Iron Silicate - (Mg, Fe)2SiO4

Hardness: 6.5–7 on Mohs scale; Color: olive green, yellowish-green to brownish; Luster: vitreous to oily; Crystal structure: orthorhombic; Cleavage: poor; Specific gravity: 3.27–4.37.

Hardness: 6
Color: olive green, yellowish-green to brownish
Luster: vitreous to oily

Identified March 23, 2026More igneous →

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Physical properties

Hardness: 6.5–7 on Mohs scale; Color: olive green, yellowish-green to brownish; Luster: vitreous to oily; Crystal structure: orthorhombic; Cleavage: poor; Specific gravity: 3.27–4.37.

Formation & geological history

Formed in the Earth's upper mantle and brought to the surface through volcanic activity (xenoliths) or tectonic uplift (ophiolites). It is one of the first minerals to crystallize from a cooling magma melt.

Uses & applications

Used as a refractory material in steel making (due to high melting point), a slag conditioner, an abrasive (sandblasting), and high-quality specimens are cut into the gemstone 'Peridot'.

Geological facts

Olivine is a primary component of the Earth's upper mantle. It has also been discovered in meteorites (pallasites) and on the Moon and Mars.

Field identification & locations

Identify in the field by its distinct 'olive' green color and granular texture. Commonly found in basaltic rocks, ultramafic intrusions, and specific sites like the Green Sand Beach in Hawaii or various volcanic regions globally.

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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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Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

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Blue Apatite

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

mineral

Magnetite

Magnetite (Fe3O4)

mineral