Magnetite (Lodestone)
Magnetite (Iron Oxide) · Mineral Specimen and Opaque Ore Mineral
Crystal System
Cubic (Isometric); typically occurs as octahedral crystals, but frequently found in massive, granular, or rounded forms like this specimen.
Mineral Group
Oxides (Spinel Group)
Chemical Formula
Fe3O4 (Iron(II,III) oxide)
Formation Process
Primarily Igneous (crystallizing from cooling magma) but also occurs in Metamorphic (contact metamorphism) and Sedimentary (as heavy mineral placer deposits) environments.
About This Crystal
An opaque, heavy mineral with a dark grey to black body color. This specimen shows a dull to sub-metallic luster on its weathered, rocky surface, with some metallic sheen visible on fresher edges. The shape is sub-angular to rounded, typical of a tumbled or water-worn pebble.
Physical Characteristics
Color: Iron black; Streak: Black; Cleavage: None (though it may show octahedral parting); Fracture: Uneven to sub-conchoidal; Specific Gravity: 5.1-5.2 (very heavy); Magnetism: Strongly magnetic.
Optical Properties
Opaque; single refraction (isotropic) when viewed in polished thin section, though generally not applicable to handheld rocky specimens. Lacks play of color or transparency.
Hardness & Durability
Origin Region
Globally distributed; notable sources include Kiruna (Sweden), Adirondack Mountains (USA), and various alluvial/river deposits where magnetic sands accumulate.
Hardness & Durability
Mohs hardness: 5.5 to 6.5. Brittle tenacity. It is durable but can be scratched by harder minerals like quartz or beryl. Susceptible to oxidation (rusting) if exposed to high moisture.
Care & Maintenance
Clean with a soft, dry cloth. Avoid prolonged exposure to water to prevent surface rusting. Keep away from electronic devices, credit cards, and mechanical watches due to its strong magnetic field.
Rarity & Value
Common; primarily valued as an iron ore in industrial contexts. Selected 'Lodestone' specimens (naturally magnetized) are valued as curiosities or educational tools, ranging from $5 to $50 depending on size and magnetic strength.
Special Characteristics
Strongly ferrimagnetic (attracts magnets). Some specimens act as natural magnets (Lodestones) capable of picking up small iron objects like paperclips.
Lore & History
Historically used in the first magnetic compasses (mariner's compass) in China and Europe. Metaphysically, it is traditionally believed to be a 'grounding' stone and used in crystal healing to align energy flows due to its magnetic properties.