Magnetite
Magnetite (IMA 1952) · Mineral Specimen / Industrial Mineral
Crystal System
Cubic (Isometric); habit is typically octahedral, but can be massive, granular, or botryoidal.
Mineral Group
Oxides (Spinel mineral group)
Chemical Formula
Fe2+Fe3+2O4
Formation Process
Primarily Igneous (magmatic segregation) and Metamorphic (contact or regional metamorphism); also occurs in hydrothermal veins and sedimentary banded iron formations.
About This Crystal
An opaque, heavy mineral with a dark grey to iron-black color. It exhibits a metallic to sub-metallic luster on fresh surfaces and often appears dull or earthy when weathered. The texture shown is massive and slightly granular with irregular surface pits.
Physical Characteristics
Color: Iron-black; Streak: Black; Cleavage: None (distinct octahedral parting); Fracture: Uneven to sub-conchoidal; Specific Gravity: 5.17–5.18; Magnetism: Strongly magnetic/ferrimagnetic; Fluorescence: None.
Optical Properties
Opaque; Refractive Index: N/A (metallic); weakly pleochroic in reflected light; typically isotropic.
Hardness & Durability
Origin Region
Found worldwide; notable sources include Kiruna (Sweden), Brazil, South Africa, and the USA (New York, Pennsylvania).
Hardness & Durability
Mohs Hardness: 5.5 to 6.5; Toughness: Brittle; Stable in most conditions but can oxidize to hematite or goethite over long periods of moisture exposure.
Care & Maintenance
Keep dry to prevent oxidation; clean with a soft brush or damp cloth; avoid ultrasonics if the piece is porous; store away from other magnetic sensitive minerals or electronic devices.
Rarity & Value
Common; Very low cost for massive specimens; value increases for well-defined octahedral crystals. Common industrial iron ore.
Special Characteristics
Naturally magnetic; some specimens act as natural magnets called 'lodestones'; ferrimagnetism is the most defining diagnostic feature.
Lore & History
Historically used by ancient Greek and Chinese civilizations for early navigation (compasses). Traditionally associated with grounding, protection, and balancing polarities in crystal healing lore.