Quartz / Common Agate

Physical Properties

Hardness: 7 (Mohs scale); Color: Tans, whites, and browns (iron-stained); Luster: Vitreous to waxy; Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & Geological History

Formed through the deposition of silica from groundwater in cavities of igneous rocks or sedimentary layers. It can be found in formations spanning various geological ages, often concentrated in alluvial deposits.

Uses & Applications

Used in landscaping, as a decorative lapidary material, in grit for abrasives, and as a common specimen for beginner rock collectors.

Geological Facts

Quartz is the second most abundant mineral in Earth's continental crust. This specimen appears to be a water-worn or weathered nodule, possibly a small agate or chalcedony pebble with a frosted exterior.

Field Identification & Locations

Identify in the field by its hardness (it will scratch glass) and waxy luster when broken. Commonly found in riverbeds, gravel pits, and beaches throughout North America and Europe.

Identified on: 4/14/2026

Mode: Standard