Quartz Vein in Host Rock

Physical Properties

Hardness: 7 on Mohs scale; Color: Milky white quartz with dark gray/black host rock; Luster: Vitreous to greasy; Crystal Structure: Trigonal/Hexagonal (though massive in this specimen); Specific Gravity: 2.65.

Formation & Geological History

Formed by hydrothermal activity where silica-rich hot fluids were injected into fractures of a pre-existing host rock. This usually occurs deep in the Earth's crust during mountain-building events (Orogeny).

Uses & Applications

Quartz is used in glassmaking, electronics (piezoelectric properties), abrasives, and as a semi-precious gemstone. Such specimens are primarily for basic collecting or decorative landscaping.

Geological Facts

Quartz is the second most abundant mineral in Earth's continental crust. Pure quartz is clear, but the 'milky' white color seen here is caused by tiny fluid inclusions of gas or liquid trapped during crystal growth.

Field Identification & Locations

Identify by its ability to scratch glass and the lack of cleavage (it breaks with a conchoidal/irregular fracture). Commonly found in areas with tectonic or volcanic history. This specific specimen shows a sharp contact between the hydrothermal quartz and the original country rock.

Identified on: 4/26/2026

Mode: Standard