Magnetite
Magnetite (Iron Oxide) · Mineral Specimen / Industrial Mineral / Collector Mineral
Crystal System
Cubic (Isometric); typically occurs as octahedral crystals, though this specimen shows a more massive, fractured habit with partially developed faces.
Mineral Group
Oxides; Spinel Group
Chemical Formula
Fe2+Fe3+2O4 (Iron(II,III) oxide)
Formation Process
Primarily Magmatic (crystallizing from cooling silicate melts as an accessory mineral) or Metamorphic (contact or regional metamorphism of iron-rich sediments).
About This Crystal
Opaque mineral with a dark grey to iron-black color and a submetallic to metallic luster. The surface in the image exhibits jagged, uneven fractures and some reflective cleavage-like parting surfaces. It has a heavy, solid appearance.
Physical Characteristics
Color: Iron-black; Streak: Black; Cleavage: None, but exhibits octahedral parting; Fracture: Uneven to subconchoidal; Specific Gravity: 5.1-5.2; Strongly Magnetic; Fluoresence: None.
Optical Properties
Opaque. In reflected light, it is grey-white with a brownish tint. It is isotropic (singly refractive) but due to opacity, standard RI testing is not applicable.
Hardness & Durability
Origin Region
Globally distributed; notable sources include Kiruna (Sweden), Brazil, South Africa, and the Adirondack Mountains (USA). Formed in igneous, metamorphic, and sedimentary environments.
Hardness & Durability
Mohs Hardness: 5.5 to 6.5; Brittle tenacity; stable under most conditions but can oxidize to hematite or goethite over long periods of moisture exposure.
Care & Maintenance
Clean with a dry, soft cloth or warm soapy water; dry immediately to preventing rusting (oxidation). Store away from magnets and electronic devices due to its magnetic field.
Rarity & Value
Very Common; low value for small raw specimens, though perfectly formed octahedral crystals are prized by collectors. Chiefly valuable as a primary ore of iron.
Special Characteristics
Strongly ferrimagnetic (attracts magnets); some specimens (lodestone) act as natural magnets themselves. No UV fluorescence.
Lore & History
Historically used as the first compasses (lodestone) by ancient mariners. Symbolically associated with grounding, manifestation, and aligning the body's magnetic field. Historically significant in the development of early metallurgy.