Magnetite (potentially in Mica matrix)
Magnetite · Mineral Specimen / Industrial Mineral
Crystal System
Cubic (Isometric); habit often octahedral, dodecahedral, or massive/granular
Mineral Group
Oxides (Spinel group)
Chemical Formula
Fe2+Fe3+2O4 (Iron(II,III) oxide)
Formation Process
Primarily magmatic (fractional crystallization in igneous rocks), hydrothermal (veins), and contact/regional metamorphic (skarns).
About This Crystal
The specimen displays a dark, metallic to sub-metallic luster with a black to dark grey color. It appears as an irregular, somewhat granular mass with evidence of planar reflections suggesting crystal faces or cleavage planes of associated minerals like biotite mica. It is opaque with a rugged, uneven surface texture.
Physical Characteristics
Color: Iron-black to silvery-grey; Streak: Black; Fracture: Subconchoidal to uneven; Specific Gravity: 5.17–5.18; Magnetism: Strongly magnetic (ferrimagnetic); Fluorescence: None.
Optical Properties
Opaque; Refractive Index: 2.42 (Metallic/Opaque); Birefringence: None (isotropic); Pleochroism: Not applicable.
Hardness & Durability
Origin Region
Notable sources include Kiruna (Sweden), Magnet Cove (Arkansas, USA), and several regions in Brazil and South Africa; occurs in igneous and metamorphic rocks.
Hardness & Durability
Mohs hardness 5.5 to 6.5. It is brittle and can be damaged by harder minerals like quartz or topaz. It is stable under normal conditions but can oxidize over long periods in moist environments.
Care & Maintenance
Avoid acidic cleaners or harsh chemicals; clean with a soft dry cloth or warm soapy water if necessary. Store in a dry environment to prevent rusting (oxidation). Keep away from delicate electronics if the specimen is naturally magnetized (Lodestone).
Rarity & Value
Very Common; low value for small specimens unless exhibiting rare octahedral crystal forms or high magnetism (Lodestone). Valued mostly as a rock-forming mineral or industrial iron ore.
Special Characteristics
Strongly magnetic; some specimens act as natural magnets (Lodestone). May show octahedral partings or twinning (spinel law).
Lore & History
Historically used in the first compasses (Lodestone) for navigation by ancient Chinese and Greek civilizations. In metaphysical lore, it is traditionally associated with 'grounding' energy, alignment, and attracting positive energy due to its magnetic properties.