Quartzite pebble

Physical Properties

Hardness: 7 on Mohs scale; Color: Tan, white, or light gray; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6 - 2.7

Formation & Geological History

Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure, typically in convergent plate boundaries (orogenic belts). This specimen likely underwent subsequent water erosion to become a rounded pebble.

Uses & Applications

Used in construction as crushed stone or road ballast, as a source for silica in glassmaking, and frequently used in landscaping. Smaller pebbles are often used in lapidary as tumbling stones.

Geological Facts

Quartzite is so durable that it often survives intense weathering that destroys other rocks. It is harder than steel and will easily scratch a glass plate.

Field Identification & Locations

Identify in the field by its inability to be scratched by a steel knife and its granular, sugary texture when broken. Commonly found in riverbeds, glacial deposits, and mountain ranges. This specific piece shows rounding characteristic of stream or beach transport.

Identified on: 4/15/2026

Mode: Standard