Magnetite (Lodestone)
Magnetite (IMA-approved name) · Mineral Specimen / Industrial Mineral
Crystal System
Cubic (Isometric); typically occurs in octahedral or dodecahedral habits, also massive or granular
Mineral Group
Oxides; Spinel Group
Chemical Formula
Fe2+Fe3+2O4 (Iron(II,III) oxide)
Formation Process
Igneous (crystallization from cooling magma), Metamorphic (contact or regional), or Hydrothermal (veins and replacement)
About This Crystal
Opaque, iron-black to brownish-black mineral with a distinct metallic to sub-metallic luster. Crystals are often missing or irregular in rough specimens, appearing as dense, heavy masses with a coarse surface texture.
Physical Characteristics
Color: Iron-black; Streak: Black; Cleavage: None (distinct octahedral parting); Fracture: Subconchoidal to uneven; Specific Gravity: 5.1-5.2; Tenacity: Brittle; Magnetism: Strongly ferromagnetic.
Optical Properties
Opaque (no refractive index for visible light); metallic luster; non-pleochroic. Highly reflective under polished light (grayish-white).
Hardness & Durability
Origin Region
Kiruna, Sweden; South Africa; Brazil; and various Adirondack locations, USA. Found in igneous and metamorphic rocks.
Hardness & Durability
Mohs hardness: 5.5 - 6.5; Toughness: Brittle; Stable in most conditions but can oxidize to hematite or goethite over long periods.
Care & Maintenance
Wash with warm soapy water only; avoid ultrasonic cleaners if fractured. Keep dry to prevent oxidation. Store away from other minerals to prevent scratching, and away from sensitive electronics due to strong magnetic field.
Rarity & Value
Common; very inexpensive as a mineral specimen. Value increases for well-formed octahedral crystals or naturally magnetized 'Lodestone' specimens.
Special Characteristics
Strongly magnetic (will attract a neodymium magnet); sometimes naturally polarized (Lodestone), allowing it to attract small iron filings or act as a natural compass.
Lore & History
Historically used by ancient Greek and Chinese mariners as the first compasses (lodestones). Traditionally associated with the Root Chakra in crystal healing, believed to have grounding and 'attracting' properties by those who use it for lore purposes.