mineral

Quartz (Milky or Smoky Quartz)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Translucent white to tan/yellowish (likely iron staining); Luster: Vitreous (glassy) to greasy; Crystal Structure: Trigonal (often massive in river pebbles); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Translucent white to tan/yellowish (likely iron staining)
Luster: Vitreous (glassy) to greasy

Identified March 19, 2026More mineral →

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Physical properties

Formation & geological history

Formed from the cooling of silica-rich magma or from hydrothermal veins. This specimen shows significant rounding, indicating it was transported by water in a fluvial (river) or beach environment. While the mineral itself can be billions of years old, the rounding occurred during recent geological processes.

Uses & applications

Used widely in glass making, electronics (due to piezoelectric properties), construction aggregates, abrasives, and as a semi-precious gemstone in jewelry or for decorative lapidary work.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. It is highly resistant to chemical and physical weathering, which is why it often remains as pebbles long after other minerals have eroded away.

Field identification & locations

Identify in the field by its hardness (it will easily scratch glass) and lack of cleavage planes. It is commonly found in gravel pits, riverbeds, and on beaches worldwide. Collectors value clear or uniquely shaped specimens.

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