mineral
Milky Quartz
Silicon Dioxide (SiO2)
Hardness: 7 Mohs; Color: Opaque white to cream; Luster: Vitreous to greasy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 Mohs
- Color
- Opaque white to cream
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 Mohs; Color: Opaque white to cream; 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 primary constituent in igneous rocks like granite. The white color comes from microscopic fluid inclusions trapped during crystal growth. Can be millions to billions of years old.
Uses & applications
Used as a source for silicon, in glass manufacturing, as a decorative landscape stone, and occasionally in lapidary work for cabochons or carving.
Geological facts
Milky quartz is the most common variety of crystalline quartz. Its opacity is caused by millions of tiny gas and liquid bubbles that scatter light within the crystal structure.
Field identification & locations
Look for a hard, white stone that cannot be scratched by a steel knife and lacks visible grains like marble. Commonly found in riverbeds, mountains, and gravel deposits globally.
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Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
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Schist
Schist
Metamorphic
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
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Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
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