mineral

Quartz Pebble

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Tan to milky white with iron staining; Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Tan to milky white with iron staining
Luster: Vitreous to waxy

Identified April 7, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 7 on Mohs scale; Color: Tan to milky white with iron staining; Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed through hydrothermal processes or via the cooling of silica-rich magma/lava. This specific specimen is a water-worn river pebble, likely formed millions of years ago and subsequently eroded and smoothed by hydraulic action in a stream or riverbed.

Uses & applications

Used in glassmaking, as an abrasive, and in the production of silicon crystals for electronics. Smooth pebbles are commonly used in landscaping, decor, and gravel production.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. These smooth, rounded shapes are the result of 'atrition,' where rocks collide and grind against each other in moving water.

Field identification & locations

Identify in the field by its ability to scratch glass, its lack of cleavage, and the conchoidal (shell-like) fracture patterns if broken. It is extremely common in riverbeds, glacial tills, and beaches worldwide.