Druzy Quartz on Chert/Chalcedony

Physical Properties

Hardness: 7 on Mohs scale; Color: White, clear, tan, and brownish-orange (iron staining); Luster: Vitreous to sparkling (druzy); Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture).

Formation & Geological History

Formed through the precipitation of silica-rich fluids in cavities or fractures within host rocks (often limestone or volcanic rock). The 'druzy' coating consists of tiny crystals that grew on a pre-existing mineral surface or chalcedony base.

Uses & Applications

Primarily used for lapidary work, jewelry (pendants and beads), and as display specimens for collectors.

Geological Facts

The term 'druzy' refers to a coating of fine crystals on a rock surface; it is from the German word 'druse', meaning a cluster of crystals in a rock cavity.

Field Identification & Locations

Identify by its 'sparkly' sugar-like appearance on a hard, dense base. It will scratch glass easily. Commonly found in riverbeds, gravel pits, and areas with limestone weathering.

Identified on: 5/1/2026

Mode: Standard