mineral

Quartz (Milky or Smoky tumble)

Crystalline Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Translucent white to light grey; Luster: Vitreous (glassy) to waxy when polished; Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Translucent white to light grey
Luster: Vitreous (glassy) to waxy when polished

Identified June 18, 2026More mineral →

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Physical properties

Formation & geological history

Quartz forms in a wide variety of environments, most commonly from the cooling of magma in igneous rocks like granite or from hydrothermal veins. This specific specimen appears to be water-worn or mechanically tumbled.

Uses & applications

Used extensively in jewelry as gemstones, in electronics for its piezoelectric properties, in glass making, and as a popular item for crystal collectors and decorative use.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. It is extremely resistant to chemical and physical weathering, which is why it is often found as smooth pebbles in riverbeds and on beaches.

Field identification & locations

Identify in the field by its hardness (it will scratch glass and steel) and its lack of cleavage. It is found globally. For collectors, look for translucent to transparent stones with a glassy luster after being wet or polished.

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Mineral/Rock

Banded Gneiss (River Rock/Pebble)

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Metamorphic Rock

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