Limonite (Goethite/Hematite mixture) with Turgite iridescence
Goethite/Hematite mixture with Turgite variety · Mineral Specimen
Crystal System
Orthorhombic (Goethite) / Trigonal (Hematite); typically occurs in massive, botryoidal, or earthy habits.
Mineral Group
Oxides and Hydroxides
Chemical Formula
FeO(OH)·nH2O (Goethite) with Fe2O3 (Hematite)
Formation Process
Secondary formation via chemical weathering and oxidation of iron-rich minerals in sedimentary and metamorphic environments.
About This Crystal
A dark, heavy mineral specimen with a sub-metallic to earthy luster. It shows a distinctive 'Turgite' iridescence (rainbow-like colors) on its weathered surfaces, contrasted against dark brown to black matte areas.
Physical Characteristics
Color: Brown to brownish-black with iridescent surface; Streak: Yellowish-brown to reddish-brown; Fracture: Conchoidal to uneven; Specific Gravity: 3.3 to 4.3; Tenacity: Brittle.
Optical Properties
Opaque; surface iridescence caused by thin-film interference on hydrated oxide layers; refractive index is typically high (2.26-2.39) but difficult to measure in massive forms.
Hardness & Durability
Origin Region
Notably from Graves Mountain, Georgia (USA), Tharsis, Spain, and various bog iron deposits worldwide.
Hardness & Durability
Mohs Hardness: 4.0 to 5.5 depending on hydration; stability is generally high but can be brittle and susceptible to scratching by quartz or steel.
Care & Maintenance
Clean only with dry brushes or compressed air; avoid prolonged exposure to water which can accelerate hydration; store in a low-humidity environment to prevent crumbling.
Rarity & Value
Locally common; value is typically low to moderate for mineral specimens, though highly iridescent 'Turgite' pieces from specific localities like Graves Mountain are sought after by collectors.
Special Characteristics
Features 'Turgite' iridescence, a multi-colored metallic sheen caused by a thin layer of hematite or goethite altering on the surface.
Lore & History
Historically mined as 'bog iron' for early iron production. In metaphysical circles, it is traditionally associated with grounding, physical endurance, and the root chakra.