mineral

Milky Quartz Pebble (Iron-stained)

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale), Color: White to brownish-orange due to iron oxide staining, Luster: Vitreous to greasy, Crystal Structure: Trigonal (Hexagonal), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Identified April 12, 2026More mineral →

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Physical properties

Formation & geological history

Formed from silica-rich hydrothermal fluids or within pegmatites. This specific specimen appears to be an alluvial pebble, meaning it was rounded by water transport in a stream or river. Many quartz deposits are millions to billions of years old.

Uses & applications

Quartz is used extensively in glassmaking, electronics (piezoelectric properties), abrasives, and as a raw material for silicon. Small pebbles like this are often collected as 'river rocks' or discarded during gold panning.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Iron staining, which gives it the yellowish-brown tint, is common when quartz is exposed to groundwater containing dissolved iron.

Field identification & locations

Identify in the field by its hardness (it will scratch glass and pocket knife blades) and lack of cleavage planes. It is commonly found in streambeds, especially by those using the gold-panning equipment seen in the background.

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