Milky Quartz with Iron Staining

Physical Properties

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

Formation & Geological History

Formed through the cooling of silica-rich hydrothermal fluids in veins or pegmatites. The yellow coloring is due to secondary iron oxide (limonite or hematite) coating the surface or filling internal fractures.

Uses & Applications

Primarily used in glass making, ceramics, and as an abrasive. While common quartz has low individual jewelry value, it is a key indicator for gold prospecting and is popular among beginning collectors.

Geological Facts

Quartz is the second most abundant mineral in Earth's continental crust. Iron-stained quartz is often called 'gold quartz' or 'rusty quartz' by prospectors because it indicates the presence of hydrothermal activity where gold might be found.

Field Identification & Locations

Identify in the field by its hardness (it will scratch glass), its conchoidal (shell-like) fracture, and its lack of cleavage. Often found in riverbeds or near mountain outcrops.

Identified on: 4/29/2026

Mode: Standard