mineral
Quartz (Iron-Stained)
Crystalline Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale), Color: Translucent to opaque orange/yellow/brown due to iron oxide impurities (limonite/hematite), Luster: Vitreous to greasy, Crystal structure: Hexagonal/trigonal, Cleavage: None (conchoidal fracture).
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Physical properties
Hardness: 7 (Mohs scale), Color: Translucent to opaque orange/yellow/brown due to iron oxide impurities (limonite/hematite), Luster: Vitreous to greasy, Crystal structure: Hexagonal/trigonal, Cleavage: None (conchoidal fracture).
Formation & geological history
Formed in hydrothermal veins or as a component of igneous rocks. The staining occurs when iron-rich groundwater permeates cracks in the quartz or when iron minerals oxidize on the surface over geological time.
Uses & applications
Industrial uses (electronics, glass-making), decorative stone, and mineral specimens for collectors.
Geological facts
Quartz is one of the most abundant minerals in Earth's crust. Specimens found in France, particularly from regions like the Alps or Massif Central, often show beautiful iron-stained patinas or 'limonite' coatings.
Field identification & locations
Identify in the field by its hardness (it scratches glass) and lack of cleavage. It is extremely common in French riverbeds, mountainous terrains, and agricultural fields as discarded cobbles.
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Other mineral specimens
Gneiss or Schist
Gneiss or Mica Schist with Garnet
Metamorphic
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Tumbled granite
Granite, a coarse-grained felsic intrusive igneous rock
igneous
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Granite
Granite (Phaneritic intrusive igneous rock)
igneous