Magnetite (with Goethite/Limonite matrix)
Magnetite · Mineral Specimen / Industrial Mineral
Crystal System
Cubic (Isometric); habit is typically octahedral or dodecahedral crystals, or massive/granular forms as seen here.
Mineral Group
Oxides (Spinel Group)
Chemical Formula
Fe2+Fe3+2O4
Formation Process
Primarily Igneous (magmatic segregation) or Metamorphic (regional or contact metamorphism of iron-rich sediments).
About This Crystal
The specimen features black, metallic to sub-metallic granular crystals embedded in a rusty yellowish-brown ochre matrix. The black crystals show octahedral facets and a vitreous to metallic luster, while the matrix is earthy and opaque.
Physical Characteristics
Color is iron-black with a black streak; the matrix has a brownish-yellow streak. Hardness is 5.5-6.5. It is strongly magnetic and has a sub-conchoidal to uneven fracture.
Optical Properties
Opaque; metallic to sub-metallic luster. It does not show pleochroism or transparency under normal conditions. Refractive index is not applicable as it is opaque.
Hardness & Durability
Origin Region
Prominent sources include Kiruna (Sweden), South Africa, and various locations in the USA (Utah, New York); forms in igneous and metamorphic environments.
Hardness & Durability
Mohs hardness of 5.5 to 6.5. It is brittle and can be damaged by harder minerals like quartz or topaz. Not typically used in jewelry due to brittleness and weight.
Care & Maintenance
Keep dry to prevent further oxidation of the iron components. Clean with a soft, dry brush; avoid water or ultrasonic cleaners which may loosen the earthy matrix.
Rarity & Value
Common mineral; value is generally low for massive specimens, though well-formed octahedral crystals command higher prices from collectors.
Special Characteristics
Strongly ferrimagnetic (lodestone is a naturally magnetized variety); may show 'schorl-like' surface striations upon close inspection.
Lore & History
Historically used in early navigation (lodestones as primitive compasses). Metaphysically associated with grounding, manifestation, and balancing polarities.