mineral

Quartz Pebble (with probable Iron staining)

Silicon Dioxide (SiO2)

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.

Hardness: 7 on Mohs scale
Color: Milky white to tan/yellow due to iron oxide impurities
Luster: Vitreous (glassy) to waxy

Identified April 13, 2026More mineral →

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Physical properties

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.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral