Quartz (River Pebble)

Physical Properties

Hardness: 7 (Mohs scale), Color: White to yellowish/tangerine (due to iron staining), Luster: Vitreous to waxy, Crystal Structure: Trigonal/Hexagonal (though massive in this habit), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Formation & Geological History

Formed from cooling silica-rich hydrothermal fluids or within igneous and metamorphic environments. This specific specimen is water-worn, indicating it was shaped by fluvial (river) or coastal erosion over centuries.

Uses & Applications

Common quartz pebbles are used in landscaping, construction aggregate, and as tumbling media. Higher purity quartz is used in glassmaking and electronics (piezoelectric properties).

Geological Facts

Quartz is one of the most abundant minerals in the Earth's crust and is highly resistant to chemical and physical weathering, which is why it is so commonly found as rounded river stones.

Field Identification & Locations

Identify in the field by its hardness (it will scratch glass) and lack of cleavage. This specimen shows 'conchodial' surface bruising from bumping against other rocks in water. Commonly found in riverbeds and beaches globally.

Identified on: 4/19/2026

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