Magnetite
Magnetite · Mineral Specimen and Important Iron Ore
Crystal System
Cubic (Isometric); habit is typically octahedral, dodecahedral, or massive/granular.
Mineral Group
Oxides (Spinel Group)
Chemical Formula
Fe2+Fe3+2O4
Formation Process
Primarily magmatic (as an accessory mineral in igneous rocks) and hydrothermal; also occurs in metamorphic rocks and as a heavy mineral in sedimentary sands.
About This Crystal
The specimen shows a massive to granular habit with a metallic to sub-metallic luster. It is opaque, displaying a dark iron-gray to black body color with a somewhat rough, fractured surface.
Physical Characteristics
Color: Iron-black. Streak: Black. Cleavage: None (has octahedral parting). Fracture: Uneven to subconchoidal. Specific Gravity: 5.17–5.18. Exceptionally magnetic.
Optical Properties
Opaque; metallic luster. In reflected light, it appears gray with a brownish tint. It is isotropic (singly refractive).
Hardness & Durability
Origin Region
Notable sources include Kiruna (Sweden), Adirondack Mountains (USA), and various localities in Brazil and South Africa.
Hardness & Durability
Mohs hardness of 5.5 to 6.5. It is brittle with poor stability toward strong acids but generally stable in sunlight and heat.
Care & Maintenance
Keep away from computers, credit cards, and electronic devices due to strong magnetism. Clean with a dry cloth or warm soapy water; avoid harsh chemicals.
Rarity & Value
Very common as a mineral but high-quality large octahedral crystals are prized by collectors. Value is generally low for massive specimens like the one pictured.
Special Characteristics
Strongly ferrimagnetic; can act as a natural magnet (lodestone). Displays metallic luster even in massive form.
Lore & History
Historically known as 'Lodestone,' used by ancient sailors for early compasses. Traditionally associated with grounding, manifestation, and balancing polarities in various mineral lore systems.