Magnetite (Lodestone)
Magnetite · Mineral Specimen / Industrial Mineral
Crystal System
Cubic (Isometric); typically occurs as octahedral crystals but also in granular or massive habits.
Mineral Group
Oxides (Spinel structural group)
Chemical Formula
Fe3O4 (Iron(II,III) oxide)
Formation Process
Typically forms via magmatic segregation in igneous rocks, regional metamorphism, or as a heavy mineral sand in sedimentary deposits.
About This Crystal
An opaque, heavy mineral with a dull to metallic luster. This specimen appears as a dark, brownish-black elongated fragment with an uneven, slightly granular surface texture and a matte finish.
Physical Characteristics
Color: Black to brownish-black; Streak: Black; Hardness: 5.5-6.5; Specific Gravity: 5.1-5.2; Strongly magnetic; Cleavage: None (has octahedral parting).
Optical Properties
Opaque; Refractive Index: 2.42 (Metallic/Semi-metallic); no pleochroism or birefringence due to opacity.
Hardness & Durability
Origin Region
Kiruna, Sweden; South Africa; Brazil; and the Adirondack Mountains, USA. Found in igneous, metamorphic, and sedimentary environments.
Hardness & Durability
Mohs hardness of 5.5-6.5; brittle toughness. Fairly stable but can react with strong acids and may oxidize to hematite (rust) over long periods in humid conditions.
Care & Maintenance
Keep dry to prevent oxidation; clean with a soft dry cloth. Avoid exposure to high heat and strong magnetic fields which can alter its natural magnetism if it is a lodestone.
Rarity & Value
Very common mineral; value is generally low for massive specimens, though well-formed octahedral crystals or naturally magnetic 'lodestone' varieties are more collectible.
Special Characteristics
Naturally ferrimagnetic; some specimens act as natural magnets (Lodestone). It is the most magnetic of all mineral species.
Lore & History
Used by ancient navigators in the first compasses (Lodestones). In lore, it is believed to be a stone of manifestation and grounding, often used to 'attract' desires and balance polarities.