Magnetite (Lodestone)
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
Formation Process
Igneous (magmatic segregation), Metamorphic (regional or contact), and occasionally in sedimentary banded iron formations
About This Crystal
Opaque, metallic to sub-metallic luster, iron-black to dark grey color. Surface often appears weathered or granular with occasional triangular faces visible in octahedral crystals.
Physical Characteristics
Color: Iron-black; Streak: Black; Cleavage: None (distinct parting on {111}); Fracture: Subconchoidal to uneven; Specific Gravity: 5.17-5.18; Strongly magnetic.
Optical Properties
Opaque; Refractive Index: 2.42 (Metallic luster); No pleochroism or birefringence as it is isotropic and opaque.
Hardness & Durability
Origin Region
Kiruna (Sweden), Adirondack Mountains (USA), various locations in South Africa, Russia, and Brazil; forms in igneous and metamorphic terrains
Hardness & Durability
Mohs Hardness: 5.5 - 6.5; Toughness: Brittle; Stable under normal conditions but can oxidize to hematite or goethite (limonite) over geologic time.
Care & Maintenance
Clean with a dry cloth or soft brush to avoid oxidation; keep away from electronics and magnetic storage media due to strong permanent magnetism.
Rarity & Value
Common; Value is generally low for massive specimens, though well-formed octahedral crystals or strong 'Lodestone' natural magnets are more collectible.
Special Characteristics
Ferrimagnetism; some specimens act as natural magnets (Lodestone) capable of attracting iron filings; its magnetism was the basis for the first compasses.
Lore & History
Historically known as 'Lodestone' and used by ancient mariners for navigation. Culturally associated with 'attraction' and grounding in traditional folkloric practices.