Magnetite with Limonite
Magnetite (var. Lodestone) / Limonite mix · Mineral Specimen / Industrial Iron Ore
Crystal System
Cubic (Isometric) for magnetite; Limonite is amorphous/cryptocrystalline. Habit: Massive, granular, and rhombohedric.
Mineral Group
Oxides / Hydroxides (Spinel Group)
Chemical Formula
Fe3O4 (Magnetite) / FeO(OH)·nH2O (Limonite)
Formation Process
Polymodal: Igneous (magmatic segregation) or Metamorphic (contact/regional). Limonite occurs via secondary weathering (oxidation).
About This Crystal
Large, dense, massive specimen featuring a dark grey-black metallic core with significant orange-brown ochreous oxidation. Luster is sub-metallic to dull. Opaque.
Physical Characteristics
Color: Iron black to rusty brown. Streak: Black (Magnetite) / Yellow-brown (Limonite). Cleavage: None (parting on {111}). Fracture: Uneven. SG: 5.17. Strongly magnetic.
Optical Properties
Opaque (no refractive index/birefringence). Metallic luster may show anisotropy in polished sections under reflected light.
Hardness & Durability
Origin Region
Kiruna (Sweden), Brazil, South Africa, or USA (Iron Range). Found in Banded Iron Formations (BIFs).
Hardness & Durability
Mohs: 5.5 - 6.5. Brittle tenacity. High durability but prone to further oxidation if moisture is present.
Care & Maintenance
Keep dry to prevent rust spread. Clean with dry brush or compressed air. Avoid acids which can dissolve iron oxides.
Rarity & Value
Very common. Value is low ($10-$50 for large rough specimens) unless exhibiting intense natural magnetism as 'Lodestone'.
Special Characteristics
Strongly ferrimagnetic (attracts magnets). May exhibit 'rusting' or secondary coatings of yellow jarosite or limonite.
Lore & History
Historically vital as the primary ore for the Iron Age. Used in early navigation (compasses). Traditionally associated with grounding and protection.