mineral

Milky Quartz (Water-worn Pebble)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Opaque white to yellowish-tan due to iron staining; Luster: Vitreous (glassy) to greasy; Crystal Structure: Hexagonal (though not visible in this tumbled form); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Opaque white to yellowish-tan due to iron staining
Luster: Vitreous (glassy) to greasy

Identified March 8, 2026More mineral →

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Physical properties

Formation & geological history

Formed in hydrothermal veins or as a primary constituent of igneous rocks like granite. This specific specimen is likely a 'river rock' or 'beach pebble,' having been eroded from its parent vein and smoothed by the action of water and sediment over thousands of years.

Uses & applications

Used in the production of glass, ceramics, and abrasives. In this rounded form, it is commonly used for landscaping, decorative gravel, and aquarium substrate. High-purity quartz is essential for electronics and solar panels.

Geological facts

Quartz is the most abundant mineral in the Earth's continental crust. Milky quartz gets its cloudy appearance from microscopic inclusions of gas or liquid trapped during the crystal's growth. Its resistance to chemical and physical weathering allows it to survive long journeys in river systems.

Field identification & locations

Identify in the field by its hardness (it will easily scratch glass) and its lack of cleavage. It is commonly found in riverbeds, glacial tills, and beaches worldwide. For collectors, look for unique patterns or unusually smooth 'moonstone' likes textures in quartz pebbles.

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