Quartz Vein in Host Rock (Breccia/Rhyolite)

Physical Properties

Hardness: 7 (quartz), 5-6 (matrix); Color: Milky white to translucent quartz, reddish-brown to grey matrix; Luster: Vitreous to dull; Crystal structure: Trigonal; Cleavage: None (conchoidal fracture).

Formation & Geological History

Formed by hydrothermal activity where silica-rich fluids filled fractures in existing volcanic or sedimentary rock. This often occurs during tectonic events or proximity to volcanic centers.

Uses & Applications

Used primarily as decorative specimens for collectors, or if high quality, as lapidary material for cabochons. Milky quartz is also a source of silica for industrial glass making.

Geological Facts

Quartz is the second most abundant mineral in Earth's continental crust. Vein quartz often acts as a host for gold, making it a primary target for historical and modern prospecting.

Field Identification & Locations

Identify in the field by its hardness (will scratch glass) and lack of cleavage. Common in mountainous regions with a history of volcanic or metamorphic activity.

Identified on: 5/11/2026

Mode: Standard