sedimentary

Quartz Pebble

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: White, cream, or off-white; Luster: Vitreous to dull/waxy; Crystal Structure: Trigonal (often worn smooth); Specific Gravity: 2.65

Hardness: 7 (Mohs scale)
Color: White, cream, or off-white
Luster: Vitreous to dull/waxy

Identified July 19, 2026More sedimentary →

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Physical properties

Hardness: 7 (Mohs scale); Color: White, cream, or off-white; Luster: Vitreous to dull/waxy; Crystal Structure: Trigonal (often worn smooth); Specific Gravity: 2.65

Formation & geological history

Formed through the weathering and erosion of quartz-bearing igneous or metamorphic rocks. These pebbles are rounded by the action of water in rivers, streams, or coastal environments over centuries to millennia.

Uses & applications

Used in landscaping, gravel for construction, water filtration, and occasionally as a source of silica for industrial manufacturing.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Rounded pebbles like this one are often referred to as 'river rocks' and their smoothness is a direct indicator of the energy and duration of the water transport they underwent.

Field identification & locations

Identify in the field by its hardness (it will scratch glass) and lack of cleavage (it breaks with a conchoidal/shell-like fracture). It is one of the most common materials found in streambeds and on beaches worldwide.