Quartzite Pebble

Physical Properties

Hardness: 7 (Mohs scale); Color: Tan, yellow-white, or buff; Luster: Vitreous to waxy; Crystal structure: Hexagonal (microcrystalline); Cleavage: None; Specific gravity: approx 2.65

Formation & Geological History

Formed through the metamorphism of quartz sandstone under high heat and pressure, causing the original quartz grains and silica cement to fuse into a dense rock. These pebbles reach this rounded shape through alluvial or coastal erosion.

Uses & Applications

Used in construction as crushed stone or gravel, in landscaping, and occasionally as an abrasive or in glass manufacturing if highly pure. Smooth pebbles like this are common in home decor and zen gardens.

Geological Facts

Quartzite is one of the hardest and most erosion-resistant rocks on the Earth's surface. Unlike sandstone, quartzite breaks through the quartz grains rather than around them due to the intense fusion during metamorphism.

Field Identification & Locations

Identify in the field by its hardness (it will easily scratch glass) and lack of reaction to acid. Often found in riverbeds, glacial deposits, and mountain outcrops. It feels denser and smoother than sandstone.

Identified on: 4/21/2026

Mode: Standard