mineral

Milky Quartz with Iron Staining

Quartz (Silicon Dioxide, SiO2)

Hardness: 7 on Mohs scale; Color: Opaque white to yellowish-brown (due to iron); Luster: Vitreous to greasy; Crystal Structure: Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Opaque white to yellowish-brown (due to iron)
Luster: Vitreous to greasy

Identified April 12, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Opaque white to yellowish-brown (due to iron); Luster: Vitreous to greasy; Crystal Structure: Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Formation & geological history

Formed in hydrothermal veins or pegmatites when silica-rich solutions cool. This specific specimen shows iron oxide staining (limonite/hematite) from weathering and exposure to groundwater.

Uses & applications

Common quartz is used as an abrasive, in glass manufacturing, and as a component in building materials like concrete and mortar.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Its name comes from the German word 'Quarz', which has Slavic origins meaning 'hard'.

Field identification & locations

Identify in the field by its inability to be scratched by a steel knife (7 hardness) and its lack of cleavage. It is found globally in almost all geological environments, particularly in river beds and weathered outcrops.

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