Yellow Quartzite (or Quartz River Pebble)

Physical Properties

Hardness: 7 (Mohs scale); Color: Yellow to brownish-orange due to iron oxide staining; Luster: Vitreous to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Formation & Geological History

Formed through the metamorphism of quartz sandstone under high heat and pressure, or as a river-worn quartz pebble that has undergone iron-rich hydration. Commonly found in alluvial deposits or metamorphic belts.

Uses & Applications

Used primarily as decorative gravel, in landscaping, as a construction aggregate, or occasionally tumbled for use in low-cost jewelry and lapidary practice.

Geological Facts

Quartzite is often stronger and more durable than the parent sandstone from which it formed. The yellow color is typically a secondary surface stain from limonite or hematite infiltrating micro-fissures in the stone.

Field Identification & Locations

Identify by its ability to scratch glass and its grainy, 'sugary' texture seen on fresh breaks. Look for it in riverbeds, glacial tills, and mountainous regions where sedimentary rocks have been squeezed.

Identified on: 4/14/2026

Mode: Standard