mineral
Ferruginous Quartz
Silicon Dioxide (SiO2) with Hematite/Limonite
Hardness: 7 (Mohs scale), Color: Reddish-brown and white/cream, Luster: Vitreous to dull, Crystal Structure: Trigonal, Cleavage: None/Conchoidal fracture, Specific Gravity: 2.6-2.7
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Physical properties
Hardness: 7 (Mohs scale), Color: Reddish-brown and white/cream, Luster: Vitreous to dull, Crystal Structure: Trigonal, Cleavage: None/Conchoidal fracture, Specific Gravity: 2.6-2.7
Formation & geological history
Formed in hydrothermal veins or as a secondary mineral in sedimentary environments where iron oxides (like hematite) precipitate onto or inside quartz crystals.
Uses & applications
Primarily collected as a mineral specimen. Polished fragments are sometimes used in lapidary work for beads or decorative stones.
Geological facts
This variety is often called 'Eisenkiesel' in German. The red color is caused by microscopic inclusions of iron oxide within the crystal lattice or between grain boundaries.
Field identification & locations
Identify by its characteristic quartz hardness (it will scratch glass) and the presence of rusty red-brown staining that does not wash off. Found globally in iron-rich geological regions.
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Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Sandstone with Mineral Veining or Crust
Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock