Quartz (Chert/Chalcedony variety)

Physical Properties

Hardness: 7 on Mohs scale; Color: Tan, white, and yellowish-translucent; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture).

Formation & Geological History

Formed from the precipitation of silica-rich fluids in volcanic cavities or sedimentary layers. This specimen appears to be a weathered nodule of chalcedony or chert, often found in ancient marine deposits or as erosional runoff.

Uses & Applications

Commonly used as an abrasive, in glass making, and as a semi-precious stone for lapidary work (tumbling/polishing).

Geological Facts

Quartz is the second most abundant mineral in Earth's continental crust. Microcrystalline varieties like this one often contain impurities that create the distinct tan and honey-like coloring.

Field Identification & Locations

Identify in the field by its hardness (will scratch glass) and lack of cleavage. Look for the 'waxy' texture on broken edges. Common in river beds and gravel pits worldwide.

Identified on: 4/14/2026

Mode: Standard