Yellow Quartzite (River Stone)

Physical Properties

Hardness: 7 (Mohs scale); Color: Yellowish-tan with sub-glassy to waxy luster; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6 - 2.8.

Formation & Geological History

Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure, where original quartz grains recrystallize into a dense interlaced structure. This specific specimen has been further shaped by fluvial (river) erosion.

Uses & Applications

Used widely in construction as crushed stone, for road ballast, and as decorative landscaping stones. Higher quality polished pieces are sold as 'healing crystals' or pocket stones.

Geological Facts

Quartzite is so tough that it often outlasts the mountain ranges it forms. It can be distinguished from its parent rock, sandstone, because it will break through the quartz grains rather than around them.

Field Identification & Locations

Identify in the field by its hardness (it will easily scratch glass) and its dense, crystalline appearance that lacks the 'gritty' feel of sandstone. This specimen is a rounded cobble commonly found in riverbeds or gravel pits.

Identified on: 4/14/2026

Mode: Standard