mineral/igneous

Magnetite with Pyroxene

Magnetite (Fe3O4) in Mafic Igneous Matrix

Hardness: 5.5-6.5; Color: Iron-black to dark grey; Luster: Metallic to submetallic; Crystal structure: Isometric (often octahedral); Specific gravity: 5.17-5.18. It is highly magnetic.

Hardness: 5
Color: Iron-black to dark grey
Luster: Metallic to submetallic

Identified June 28, 2026More mineral/igneous →

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Physical properties

Hardness: 5.5-6.5; Color: Iron-black to dark grey; Luster: Metallic to submetallic; Crystal structure: Isometric (often octahedral); Specific gravity: 5.17-5.18. It is highly magnetic.

Formation & geological history

Typically forms as a primary mineral in igneous rocks like basalt and gabbro through magmatic segregation, or in metamorphic rocks and hydrothermal veins. Often found in Precambrian banded iron formations.

Uses & applications

Primary ore of iron; used in heavy media separation, as a pigment in concrete, and for magnetic storage media.

Geological facts

Magnetite is the most magnetic of all the naturally-occurring minerals on Earth. Naturally magnetized pieces called lodestones were used as the first compasses.

Field identification & locations

Identify in the field using a handheld magnet; it will be strongly attracted. Look for black streak and high density. Found worldwide in iron mining districts like those in Sweden, South Africa, and the Lake Superior region.

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mineral/igneous

Quartz with inclusions (likely Chlorite or Hornblende) and country rock

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FeS2 (Iron Pyrite) with SiO2 (Quartz)

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Labradorite (likely Black Labradorite or Larvikite)

Labradorite (Na,Ca)(Al,Si)4O8. If a rock, it is typically anorthosite, gabbro, or norite, or a variety of syenite called Larvikite if it is specifically from Larvik, Norway.

Mineral/Igneous Rock

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Fluorapatite (Ca5(PO4)3F)

mineral

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mineral