mineral

Magnetite (Lodestone)

Magnetite (Fe3O4)

Hardness: 5.5-6.5; Color: Iron-black to silvery-gray; Luster: Metallic to sub-metallic; Crystal structure: Isometric (often octahedral); Cleavage: None (has parting); Specific Gravity: 5.1-5.2

Hardness: 5
Color: Iron-black to silvery-gray
Luster: Metallic to sub-metallic

Identified July 17, 2026More mineral →

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Physical properties

Hardness: 5.5-6.5; Color: Iron-black to silvery-gray; Luster: Metallic to sub-metallic; Crystal structure: Isometric (often octahedral); Cleavage: None (has parting); Specific Gravity: 5.1-5.2

Formation & geological history

Formed in igneous, metamorphic, and sedimentary environments. It commonly crystallizes as an accessory mineral in igneous rocks like basalt and gabbro, or through hydrothermal replacement in contact metamorphic zones. Lodestone variants are formed when lightning strikes magnetite-rich outcrops.

Uses & applications

Major ore of iron; used in heavy media separation, water filtration, industrial abrasives, toner for laser printers, and magnetic recording media. Rarely used in jewelry due to brittleness.

Geological facts

Magnetite is the most magnetic of all naturally occurring minerals. The naturally magnetized variety, Lodestone, was used by early mariners to create the first compasses. It is sometimes found as bio-magnetite in the brains of birds and bees to help with navigation.

Field identification & locations

Identify by its strong attraction to magnets. It leaves a black streak on a streak plate. Commonly found in black sands along rivers or beaches and within large banded iron formations. Collectors look for well-defined octahedral crystals.