mineral
Milky Quartz
Silicon Dioxide (SiO2)
Hardness: 7 Mohs; Color: White/Translucent; Luster: Vitreous to Greasy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.65
- Hardness
- 7 Mohs
- Color
- White/Translucent
- Luster
- Vitreous to Greasy
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Physical properties
Hardness: 7 Mohs; Color: White/Translucent; Luster: Vitreous to Greasy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.65
Formation & geological history
Forms in hydrothermal veins or as a late-stage crystallization in igneous rocks like pegmatites. Found in all types of geological environments and can be any age from Precambrian to Cenozoic.
Uses & applications
Used as an abrasive, in glass manufacturing, as a source of silica for computer chips, and commonly as gravel or landscaping stone. Higher quality milky quartz is used for carvings or beads.
Geological facts
Milky quartz gets its white, opaque appearance from tiny microscopic inclusions of gas or liquid trapped during crystal growth. It is the most common variety of crystalline quartz.
Field identification & locations
Identify in the field by its hardness (cannot be scratched by steel), lack of cleavage, and white color. It is globally ubiquitous and often found as rounded pebbles in stream beds or as veins in primary rock outcrops.
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Other mineral specimens
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
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic