Quartz Pebble (with probable Iron staining)

Physical Properties

Hardness: 7 on Mohs scale; Color: Milky white to tan/yellow due to iron oxide impurities; Luster: Vitreous (glassy) to waxy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65.

Formation & Geological History

Formed from silica-rich hydrothermal fluids or within igneous and metamorphic rocks. This specific specimen is a water-worn river pebble, likely millions of years old, weathered and smoothed by water transport.

Uses & Applications

Used in construction as aggregate, in glassmaking, and as an abrasive. While this pebble is common, high-quality quartz is used in jewelry and electronics (piezoelectric properties).

Geological Facts

Quartz is the second most abundant mineral in Earth's continental crust. The yellow/orange tint is often caused by 'limonite' or iron oxide staining the surface or cracks of the stone.

Field Identification & Locations

Identify in the field by its inability to be scratched by a steel knife and lack of cleavage. It is extremely common in riverbeds, beaches, and gravel pits worldwide.

Identified on: 4/13/2026

Mode: Standard