mineral

Magnetite Sand (Black Sand)

Magnetite (Fe3O4)

Hardness: 5.5-6.5; Color: Black to silvery gray; Luster: Metallic to submetallic; Crystal Structure: Isometric; Strongly magnetic; Cleavage: Indistinct; Specific Gravity: 5.1-5.2

Hardness: 5
Color: Black to silvery gray
Luster: Metallic to submetallic

Identified May 16, 2026More mineral →

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Physical properties

Hardness: 5.5-6.5; Color: Black to silvery gray; Luster: Metallic to submetallic; Crystal Structure: Isometric; Strongly magnetic; Cleavage: Indistinct; Specific Gravity: 5.1-5.2

Formation & geological history

Formed in igneous, metamorphic, and sedimentary environments. It is a common accessory mineral in igneous rocks like granite and basalt. As it is resistant to weathering, it often accumulates as heavy mineral placer deposits in riverbeds and beach sands.

Uses & applications

Major ore of iron for steel production. Used in water filtration, heavy media separation for coal washing, and as a pigment. Also used in industrial magnets and as a specimen for education/physics demonstrations.

Geological facts

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

Field identification & locations

Easily identified in the field by its strong attraction to a magnet (as seen in the image) and its black streak. Often found in heavy mineral concentrates at the bottom of gold pans or as dark streaks on shorelines.