Magnetite
Magnetite (Iron Oxide) · Mineral Specimen / Industrial Mineral
Crystal System
Cubic (Isometric); typically occurs as octahedral crystals, massive, or granular habits.
Mineral Group
Oxides; Spinel Group
Chemical Formula
Fe2+Fe3+2O4
Formation Process
Primarily Magmatic (crystallizing from cooling magma) but also occurs through Hydrothermal and Metamorphic processes.
About This Crystal
Black to brownish-black metallic mineral with a submetallic to metallic luster. It is typically opaque with a granular or crystalline surface. The specimen shows significant metallic sheen and uneven, jagged fractures.
Physical Characteristics
Color: Iron-black to dark grey; Streak: Black; Cleavage: None (distinct octahedral parting); Fracture: Uneven to subconchoidal; Specific Gravity: 5.17–5.18; Magnetic: Strongly ferrimagnetic; Hardness: 5.5–6.5.
Optical Properties
Opaque; Refractive index is not applicable as it is not transparent; Metallic luster; No pleochroism or birefringence visible.
Hardness & Durability
Origin Region
Global; notable specimens from Kiruna (Sweden), South Africa, USA (New York, Utah, Pennsylvania), and Brazil. Found in igneous, metamorphic, and sedimentary rocks.
Hardness & Durability
Mohs hardness of 5.5 to 6.5. Relatively brittle and hard, but lacks cleavage which makes it somewhat durable as a mineral specimen.
Care & Maintenance
Keep dry to prevent oxidation (rusting) if iron content is high. Clean with a soft brush and avoid harsh chemicals. Store away from other minerals that may be scratched/impacted by its magnetic field.
Rarity & Value
Common; high industrial value as an iron ore. Specimen value is generally low unless forming perfect octahedral crystals or 'loadstone' varieties.
Special Characteristics
Strongly magnetic (ferrimagnetism); some specimens act as natural magnets (Lodestones) which can attract iron filings or pins.
Lore & History
Historically used in the first compasses (Lodestone) by ancient Chinese and Greek navigators. Medicinally mentioned by Pliny the Elder. In folklore, it is associated with 'attraction' and grounding due to its magnetic nature.