Quartz (Iron-stained or Milky Quartz)

Physical Properties

Hardness: 7 on Mohs scale; Color: Milky white to translucent with yellow/brown iron oxide staining; Luster: Vitreous (glassy) to greasy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Formation & Geological History

Formed through the cooling of magma or hydrothermal activity in veins. It is one of the most abundant minerals in the Earth's crust and can be found in rocks from virtually all geological ages.

Uses & Applications

Used in glassmaking, abrasives, foundry sand, and hydraulic fracturing proppant. Clearer varieties are used in jewelry (as citrine or amethyst) or as metaphysical 'healing crystals' for collectors.

Geological Facts

Quartz is chemically and physically stable at the Earth's surface, which is why it is the primary component of most beach sand. The gold-colored staining seen in this specimen is caused by liquid iron impurities seeping into micro-cracks.

Field Identification & Locations

Identify in the field by its inability to be scratched by a steel knife (hardness 7) and its lack of cleavage. It is found globally, extremely common in mountainous regions and riverbeds.

Identified on: 4/15/2026

Mode: Standard