Magnetite
Magnetite (IMA-approved mineral species name) · Mineral Specimen / Industrial Mineral / Metallic Ore
Crystal System
Cubic (Isometric); habit is typically octahedral or dodecahedral crystals, but commonly occurs in granular to massive forms as seen in this specimen.
Mineral Group
Oxides (Spinel Group)
Chemical Formula
Fe2+Fe3+2O4 (Iron(II,III) oxide)
Formation Process
Igneous (magmatic segregation), Metamorphic (contact and regional), or Hydrothermal. Formed under varying temperatures in magmas or through contact metamorphism of iron-rich sediments.
About This Crystal
The specimen displays a characteristic dark grey to black color with a dull to sub-metallic luster. It has a granular, massive texture without distinct crystal faces. It is opaque with an uneven, rough surface morphology.
Physical Characteristics
Color: Iron-black to dark grey; Streak: Black; Cleavage: None (distinct octahedral parting may occur); Fracture: Uneven to sub-conchoidal; Specific Gravity: 5.17-5.18; Tenacity: Brittle; Magnetism: Strongly magnetic (ferrimagnetic); Fluorescence: Generally none.
Optical Properties
Opaque; Refractive index is not applicable for opaque minerals; exhibits no pleochroism or dispersion in hand specimen; isotropic (singly refractive under polished section).
Hardness & Durability
Origin Region
Kiruna (Sweden), Adirondack Mountains (USA), Bushveld Complex (South Africa), and various hydrothermal and sedimentary deposits worldwide.
Hardness & Durability
Mohs hardness: 5.5 - 6.5. Toughness is generally brittle. High stability but can rust (oxidize to hematite or limonite) if exposed to moisture over long periods.
Care & Maintenance
Clean with a soft dry cloth; avoid long-term exposure to water or acids which can cause oxidation. Store in a dry place. Keep away from magnetic media (credit cards, hard drives) due to its strong magnetic field.
Rarity & Value
Common; very affordable as mineral specimens ($5-$30 for hand samples). Value increases for well-formed octahedral crystals or lodestone (naturally magnetized) varieties.
Special Characteristics
Strongly attracted to magnets; some specimens (lodestone) act as natural magnets themselves. It is the most magnetic of all naturally occurring minerals on Earth.
Lore & History
Historically used as the earliest form of a magnetic compass (lodestone). In lore, it is believed to be a 'grounding' stone. Ancient Greeks and Romans were aware of its properties; it was named after Magnes, a Greek shepherd who found it attracted the iron tip of his staff.