mineral

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2) with Limonite/Goethite

Hardness: 7 on Mohs scale; Color: White to translucent with yellow-orange staining; Luster: Vitreous to greasy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: White to translucent with yellow-orange staining
Luster: Vitreous to greasy

Identified May 6, 2026More mineral →

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Physical properties

Formation & geological history

Formed through hydrothermal processes where silica-rich fluids crystallized in veins or cooling igneous bodies. The yellow staining is caused by secondary oxidation of iron-bearing minerals (like pyrite) into limonite or goethite.

Uses & applications

Used in glassmaking, abrasives, and as a gemstone (when clear or specifically colored). In this form, it is primarily a collector's specimen or used for landscaping and industrial silicon production.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Iron-stained quartz is often found near gold-bearing veins, making it a classic indicator for prospectors.

Field identification & locations

Identify in the field by its hardness (it will scratch glass), lack of cleavage, and the characteristic rusty-yellow 'iron cap' coloring. It is commonly found in mountain ranges, riverbeds, and mine tailings globally.

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