Magnetite in Matrix
Magnetite (Iron Oxide) · Mineral Specimen / Industrial Mineral
Crystal System
Cubic (Isometric); typically occurs as octahedral crystals, granular masses, or rounded grains
Mineral Group
Oxides (Spinel Group)
Chemical Formula
Fe2+Fe3+2O4
Formation Process
Primarily Igneous (magmatic segregation) or Metamorphic (contact or regional metamorphism). Also found in hydrothermal veins and as a heavy mineral in sedimentary 'black sands'.
About This Crystal
The specimen features a dark, metallic, opaque mineral grain embedded in a dark grey-to-black fine-grained matrix. The luster of the inclusion is sub-metallic to metallic, with a slightly granular or pitted surface texture. Surrounding matrix shows some yellowish-brown oxidation and lighter silicate inclusions.
Physical Characteristics
Color: Iron-black to dark grey; Streak: Black; Hardness: 5.5-6.5; Specific Gravity: 5.1-5.2; Tenacity: Brittle; Magnetism: Strongly magnetic (diagnostic); Cleavage: None (has octahedral parting).
Optical Properties
Opaque; Refractive Index: N/A (metallic); Luster: Metallic to sub-metallic; No pleochroism or birefringence as it is an isometric oxide.
Hardness & Durability
Origin Region
Found globally; notable sources include Kiruna (Sweden), South Africa, and the Lake Superior region (USA). This specimen appears as a massive inclusion in a basaltic or metamorphic matrix.
Hardness & Durability
Mohs hardness of 5.5 to 6.5. Good durability but susceptible to oxidation (rusting) if exposed to moisture over long periods. Brittle tenacity makes it prone to chipping.
Care & Maintenance
Keep dry to prevent oxidation. Clean with a soft, dry brush. Avoid acidic cleaners which can react with iron oxides. Store away from other minerals that could be scratched by its 6.5 hardness.
Rarity & Value
Common mineral worldwide. Value is generally low for small grains in matrix, primarily determined by crystal perfection (octahedrons) or as a bulk industrial ore for iron production.
Special Characteristics
Strongly magnetic; some specimens act as natural magnets (Lodestone). May exhibit sub-metallic 'twinkling' under direct light due to granular crystal faces.
Lore & History
Historically significant as the first substance used to create compasses (Lodestone) by ancient Chinese and Greek civilizations. Traditionally associated with grounding, stability, and the root chakra in crystal lore.