Mineral

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: Tan/Translucent; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Tan/Translucent
Luster: Vitreous to waxy

Identified March 24, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: Tan/Translucent; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed through hydrothermal processes or igneous cooling, then weathered and smoothed through fluvial (river) transport over thousands of years.

Uses & applications

Common quartz is used in construction as aggregate, in glass manufacturing, for electronics (piezoelectric properties), and as tumbled stones for decorative use.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Rounded specimens like this are often called 'river rocks' because water action has eroded all sharp crystal edges.

Field identification & locations

Identify in the field by its hardness (it should scratch glass) and lack of cleavage. Found globally in riverbeds, beaches, and glacial deposits. Collector tip: look for internal 'fires' or clarity when held to light.