Magnetite
Magnetite · Mineral Specimen / Industrial Mineral
Crystal System
Cubic (Isometric); common habits include octahedral crystals, granular masses, and massive forms.
Mineral Group
Oxides; Spinel Group
Chemical Formula
Fe2+Fe3+2O4
Formation Process
Primarily Igneous (magmatic segregation) and Metamorphic (contact and regional metamorphism); also found in hydrothermal veins and sedimentary banded iron formations.
About This Crystal
An opaque mineral with a metallic to sub-metallic luster. The specimen shown is a dark grey to black granular mass with a somewhat dull, rough surface texture and some minor metallic highlights in recessed areas.
Physical Characteristics
Color: Iron-black to dark grey; Streak: Black; Fracture: Uneven to sub-conchoidal; Specific Gravity: 5.17–5.18; Fluorescence: None; Key feature: Strongly magnetic.
Optical Properties
Opaque; metallic luster; shows no pleochroism or birefringence in hand specimen. Refractive index is not applicable as it is opaque.
Hardness & Durability
Origin Region
Notable sources include Kiruna (Sweden), Adirondack Mountains (USA), and various localities in Brazil and South Africa; found in igneous and metamorphic rocks.
Hardness & Durability
Mohs hardness: 5.5 to 6.5. It is relatively brittle with poor cleavage, making it sturdy but prone to chipping.
Care & Maintenance
Keep dry to prevent oxidation/rusting over long periods. Clean with a soft brush or micro-fiber cloth; avoid harsh acids like HCl which can dissolve the mineral.
Rarity & Value
Very common mineral; value is generally low for massive/granular specimens, though well-formed octahedral crystals are prized by collectors.
Special Characteristics
Strongly ferrimagnetic (attracted to magnets); some specimens (lodestone) act as natural magnets themselves.
Lore & History
Historically used in the first compasses (lodestone). In metaphysical lore, it is believed to be a grounding stone that aligns the chakras and utilizes magnetic energy to balance the body.