Magnetite
Magnetite (IMA-approved mineral name) · Collector Mineral and Industrial Mineral (primary ore of iron)
Crystal System
Cubic (Isometric); commonly forms octahedral crystals, dodecahedral faces, or massive/granular aggregates.
Mineral Group
Oxides (Spinel subgroup of the Oxides and Hydroxides class)
Chemical Formula
Fe2+Fe3+2O4
Formation Process
Primarily Igneous (magmatic segregation or accessory mineral) and Metamorphic (regional or contact metamorphism). Also found in hydrothermal veins and concentrated in sedimentary heavy mineral sands.
About This Crystal
Opaque, iron-black to dark brownish-gray mineral with a metallic to sub-metallic luster. It often appears as compact, granular masses or well-defined octahedral crystals. The surface can exhibit a dull tarnish or slight oxidation.
Physical Characteristics
Color: Iron-black. Streak: Black. Cleavage: None (exhibits octahedral parting). Fracture: Conchoidal to uneven. Specific Gravity: 5.17–5.18. Most notable characteristic is its strong ferrimagnetism.
Optical Properties
Opaque (does not transmit light). In reflected light, it is gray-white with a brownish tint. It is isotropic (no birefringence) due to its cubic crystal system.
Hardness & Durability
Origin Region
Notable sources include Kiruna (Sweden), Brazil, South Africa, Ural Mountains (Russia), and the Adirondack Mountains (USA). Found in igneous, metamorphic, and sedimentary environments.
Hardness & Durability
Mohs hardness: 5.5–6.5. Brittle tenacity. Sensitive to strong acids; relatively stable but can oxidize to hematite or goethite over long periods in moist environments.
Care & Maintenance
Clean with a dry cloth or warm soapy water; dry immediately to prevent oxidation. Keep away from electronic devices and magnetic media due to its strong magnetic field. Store separately from softer stones.
Rarity & Value
Common mineral worldwide. Value is generally low for massive specimens but higher for well-formed octahedral crystals or 'lodestone' varieties (naturally magnetized magnetite). Not typically treated.
Special Characteristics
Strongly magnetic (attracted to magnets); the variety 'lodestone' acts as a permanent magnet. Exhibits piezoelectric properties under certain conditions and can show octahedral parting.
Lore & History
Historically used in the first compasses (lodestones) by ancient Greek and Chinese navigators. Symbolically associated with grounding and attraction in traditional folklore. Often linked to the Root Chakra in crystal healing practices.