mineral

Magnetite (Octahedral Crystal)

Magnetite (Fe3O4)

Hardness: 5.5-6.5; Color: Iron-black to dark gray; Luster: Metallic to submetallic; Crystal Structure: Isometric (often octahedral); Specific Gravity: 5.1-5.2; Streak: Black

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

Identified July 17, 2026More mineral →

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Physical properties

Hardness: 5.5-6.5; Color: Iron-black to dark gray; Luster: Metallic to submetallic; Crystal Structure: Isometric (often octahedral); Specific Gravity: 5.1-5.2; Streak: Black

Formation & geological history

Formed in igneous, metamorphic, and sedimentary environments. Typically occurs as an accessory mineral in igneous rocks like granite or basalt, or through contact metamorphism. Highly resistant to weathering.

Uses & applications

Primary ore of iron; used in heavy media separation, as a pigment, and in industrial abrasives. Specimens with good crystal form are popular in mineral collecting.

Geological facts

Magnetite is the most magnetic of all the naturally-occurring minerals on Earth. Some varieties, known as lodestone, act as natural magnets and were used in the first compasses.

Field identification & locations

Identified by its strong attraction to magnets, black streak, and characteristic double-pyramid octahedral shape. Common in the iron ranges of the USA, Brazil, Australia, and Sweden.