Magnetite
Magnetite (IMA approved) · Collector Mineral and Industrial Mineral (Iron Ore)
Crystal System
Cubic (Isometric); crystals are often octahedral, but this specimen shows a massive to granular habit with metallic surface sheen.
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 metamorphism of iron-rich sediments), or Hydrothermal (concentrated in veins).
About This Crystal
An opaque, heavy mineral with a dark grey to black color and a noticeable sub-metallic to metallic luster. The surface appears granular and reflective, typical of iron oxide minerals.
Physical Characteristics
Color: Iron-black; Streak: Black; Cleavage: None (distinct octahedral parting possible); Fracture: Uneven to sub-conchoidal; Specific Gravity: 5.17–5.18; Magnetism: Strongly magnetic; Fluorescence: None.
Optical Properties
Opaque; metallic luster; isotropic (singly refractive); no pleochroism or dispersion effects visible due to opacity.
Hardness & Durability
Origin Region
Found globally; notable sources include Kiruna (Sweden), Brazil, and the Adirondack Mountains (USA). Most common in igneous and metamorphic rocks.
Hardness & Durability
Mohs hardness: 5.5 to 6.5. It is relatively brittle but durable enough for handling as a specimen. Brittle tenacity.
Care & Maintenance
Keep dry to prevent oxidation (rusting) over long periods. Clean with a dry brush or damp cloth. Store separately from magnets and electronic devices due to its magnetic field.
Rarity & Value
Very common as an ore; large, well-formed octahedral crystals are more valuable for collectors. Generally inexpensive in massive form.
Special Characteristics
Strongly ferrimagnetic (attracts magnets); some specimens (lodestone) act as natural magnets. High specific gravity makes it feel unexpectedly heavy for its size.
Lore & History
Historically used in the first compasses (lodestone) by ancient Chinese and Greek navigators. In crystal healing lore, it is believed to be a 'grounding' stone that aligns the chakras and balances polarities.