mineral

Quartz Pebble (Chert/Chalcedony)

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: Milky white to translucent tan; Luster: Waxy to vitreous; Crystal Structure: Hexagonal (microcrystalline/cryptocrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Milky white to translucent tan
Luster: Waxy to vitreous

Identified April 11, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the precipitation of silica-rich fluids in volcanic or sedimentary rocks. This specific specimen shows signs of fluvial or coastal erosion, which has rounded its edges into a smooth pebble over thousands of years.

Uses & applications

Used primarily as decorative landscape stone, in glass manufacturing, and as a common find for gemstone tumbling. Higher quality varieties are used in jewelry.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. This specimen is likely a piece of 'milky quartz' or 'chert' that has been water-worn. If it is high in silica and microcrystalline, it may be classified as chalcedony.

Field identification & locations

Identify in the field by its hardness (it will scratch glass) and its characteristic conchoidal fracture (curved, glass-like breaks). It is frequently found in riverbeds, glacial tills, and along beaches.

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