mineral
Milky Quartz
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: Milky white to tan; Luster: Vitreous to greasy; Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Milky white to tan
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 on Mohs scale; Color: Milky white to tan; Luster: Vitreous to greasy; Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Forms in hydrothermal veins or as a major constituent of igneous rocks like granite. The milky appearance is caused by tiny inclusions of gas or liquid trapped during crystal growth.
Uses & applications
Used as a source of silica for glassmaking, sandpaper, and ceramics; also popular in landscaping and as a mineral specimen for collectors.
Geological facts
Milky quartz is the most common variety of crystalline quartz. Historically, it was used by many ancient cultures to make stone tools due to its hardness and sharp fracture edges.
Field identification & locations
Identify in the field by its hardness (it can scratch glass), the lack of cleavage, and its often translucent to opaque white appearance. Often found as rounded pebbles in riverbeds or as veins in mountain ranges.
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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