mineral
Milky quartz (rough quartz crystal)
Quartz, silicon dioxide (SiO₂)
AI-generated identification · may be incorrectTypically hardness 7 Mohs, white to translucent gray, vitreous luster, and a hexagonal crystal structure; it has indistinct cleavage and prominent conchoidal fracture. The specimen appears massive and weathered, with possible iron-oxide staining or attached matrix.
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Physical properties
Typically hardness 7 Mohs, white to translucent gray, vitreous luster, and a hexagonal crystal structure; it has indistinct cleavage and prominent conchoidal fracture. The specimen appears massive and weathered, with possible iron-oxide staining or attached matrix.
Formation & geological history
Forms when silica-rich hydrothermal fluids fill fractures and cavities, or crystallizes in igneous and metamorphic rocks. Quartz is common from Precambrian to modern geological environments and is found worldwide.
Uses & applications
Used in glass, ceramics, electronics, abrasives, engineered stone, and limited jewelry; attractive transparent pieces are collectible, while ordinary rough material is inexpensive.
Geological facts
Milky color results from microscopic fluid inclusions, fractures, or impurities scattering light. Quartz is one of Earth’s most abundant and chemically durable minerals.
Field identification & locations
Identify by its glassy appearance, lack of cleavage, conchoidal fracture, and ability to scratch ordinary glass; a steel knife should not scratch it. Common localities include Brazil, Madagascar, the United States, and alpine or hydrothermal veins.
