mineral

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: White, translucent to opaque with reddish-brown iron oxide stains; Luster: Vitreous to greasy; Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 (Mohs scale)
Luster: Vitreous to greasy

Identified June 14, 2026More mineral →

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Physical properties

Formation & geological history

Formed from silica-rich hydrothermal fluids cooling in veins or as a major constituent of igneous rocks like granite. This specific specimen shows weathering and oxidation (limonite/hematite staining) likely from being near the surface or in a streambed.

Uses & applications

Used in glass manufacturing, electronics (due to piezoelectricity), construction aggregate, and as a raw material for silicon production. Low-grade specimens are used in landscaping.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Pure quartz is clear, but tiny fluid inclusions during formation create the 'milky' white appearance seen here.

Field identification & locations

Identify in the field by its hardness (it can scratch glass), lack of cleavage, and glassy luster on fresh surfaces. It is found globally across all geological environments.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

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

Granite

Granite (Phaneritic intrusive igneous rock)

igneous