Orange Quartzite (River Pebble)

Physical Properties

Hardness: 7 on Mohs scale; Color: Orange to peach-tan; Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal (granular microcrystalline structure); Cleavage: None (conchoidal fracture); Specific gravity: ~2.65.

Formation & Geological History

Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause quartz grains to recrystallize and fuse into a dense rock. This specimen appears as a river-worn pebble, indicating it was eroded from its source and tumbled smooth by water over thousands of years.

Uses & Applications

Commonly used as decorative landscaping stone, in construction aggregates, or as tumbled 'pocket stones' for collectors. High-purity quartzite is used to produce silica sand for glassmaking and industrial abrasives.

Geological Facts

Quartzite is so tough that it often outlasts the surrounding rock, forming steep ridges or caps on mountains. Unlike sandstone, which breaks around its grains, quartzite breaks through the grains because the bond between them is so strong.

Field Identification & Locations

Identify in the field by its hardness (it can easily scratch glass) and its sugary, granular texture that sparkles slightly under light. It will not fizz when exposed to acid, which distinguishes it from marble.

Identified on: 4/13/2026

Mode: Standard