Magnetite with Iron-rich Gossan
Magnetite (Iron oxide species) · Industrial Mineral and Mineral Specimen
Crystal System
Cubic (Isometric); typical habit is octahedral, but commonly found as granular or massive aggregates as shown in the image.
Mineral Group
Oxides (Spinel Group)
Chemical Formula
Fe3O4 (Iron(II,III) oxide)
Formation Process
Igneous/Metamorphic: Forms through magmatic segregation in cooling silicate melts or during contact/regional metamorphism of iron-rich sediments.
About This Crystal
The specimen presents as dark gray to black, metallic to sub-metallic crusts and granular masses. It is opaque with a somewhat dull, earthy luster on weathered surfaces and resides on a brownish-red ferruginous matrix (gossan) characterized by iron oxidation.
Physical Characteristics
Color: Iron-black to dark gray; Streak: Black; Cleavage: None (distinct octahedral parting); Fracture: Subconchoidal to uneven; Specific Gravity: 5.17–5.18; Magnetism: Strongly magnetic/ferromagnetic; Fluorescence: None.
Optical Properties
Opaque (does not transmit light); Refractive Index: N/A (metallic mineral); can show slight anisotropy in polished sections under reflected light.
Hardness & Durability
Origin Region
Prominent sources include Kiruna (Sweden), Canada, and various regions of the United States; typically found in igneous and metamorphic rocks or as heavy sands.
Hardness & Durability
Mohs Hardness: 5.5 to 6.5; Toughness: Brittle; Stable under normal conditions, though susceptible to oxidation/rusting if exposed to moisture over long periods.
Care & Maintenance
Clean with a dry brush or compressed air; avoid prolonged exposure to water which may cause localized rusting. Store in a dry environment and keep away from high-temperature sources.
Rarity & Value
Common mineral; value as a specimen is relatively low unless found in well-formed octahedral crystals. Highly valuable as a primary ore of iron for industrial use.
Special Characteristics
Strongly attracted to magnets; some specimens (lodestone) act as natural magnets themselves. Exhibits a 'metallic-earthy' duality depending on the degree of surface weathering.
Lore & History
Historically used by early mariners as 'lodestone' for the first compasses. In metaphysical traditions, it is believed to be a 'grounding' stone that aligns the chakras and balances polarities due to its magnetic nature.