Quartz Pebble (Iron-stained)

Physical Properties

Hardness: 7 (Mohs scale), Color: Tans, yellows, and white due to iron oxide staining, Luster: Vitreous to waxy, Crystal structure: Trigonal/Hexagonal (microcrystalline/cryptocrystalline in this form), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Formation & Geological History

Formed through hydrothermal processes or within igneous rocks (like granite) and subsequently weathered and rounded by water transport (fluvial/river action). The yellow/brown tint comes from secondary iron oxide staining (limonite/hematite) after it was exposed to the surface.

Uses & Applications

Common quartz is used widely in construction (sand/aggregate), glass making, and as an abrasive. Smooth river pebbles are often used in landscaping or as decorative stones in aquariums.

Geological Facts

Quartz is the second most abundant mineral in Earth's continental crust. These rounded pebbles are often called 'river stones' and have been smoothed over hundreds or thousands of years by the abrasive action of water and sediment.

Field Identification & Locations

Identify in the field by its hardness (it will scratch glass and steel), lack of cleavage, and smooth, rounded exterior. It is commonly found in riverbeds, glacial tills, and along beaches worldwide.

Identified on: 4/13/2026

Mode: Standard