mineral

Magnetite / Lodestone

Magnetite (Fe3O4)

AI-generated identification · may be incorrect

Mohs hardness: 5.5-6.5; Color: Dark grey to black, metallic sub-shiny; Luster: Metallic to sub-metallic; Streak: Black; Specific Gravity: ~5.18; Crystal System: Isometric (octahedral when crystallized). Strongly magnetic.

Hardness: 5
Color: Dark grey to black, metallic sub-shiny
Luster: Metallic to sub-metallic

Identified July 25, 2026More mineral →

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Physical properties

Formation & geological history

Forms in igneous, metamorphic, and sedimentary rocks as an accessory mineral or concentrated ore deposit, often through magmatic segregation or hydrothermal replacement.

Uses & applications

Primary ore of iron; used in heavy media separation, water filtration, industrial pigments, and as natural magnetic specimens (lodestone) for education and collecting.

Geological facts

Magnetite is the most magnetic naturally-occurring mineral on Earth. Naturally magnetized pieces called lodestones were used to create the earliest magnetic compasses in ancient history.

Field identification & locations

Identified in the field by its strong attraction to magnets, heavy feel (high specific gravity), black streak, and dark metallic-to-dull surface appearance.