mineral

Milky Quartz Pebble with Iron staining

Silicon Dioxide (SiO2)

Color: Opaque white with reddish-brown oxidation; Hardness: 7 on Mohs scale; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Opaque white with reddish-brown oxidation
Luster: Vitreous to waxy

Identified June 14, 2026More mineral →

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Physical properties

Formation & geological history

Formed in hydrothermal veins or as a secondary mineral in igneous and metamorphic rocks. The pebble's rounded shape indicates it has been tumbled by water in a stream or beach environment. The red staining is likely iron oxide (limonite or hematite).

Uses & applications

Used in construction for gravel and concrete, in the glass industry as a source of silica, and as decorative garden stones. Larger specimens can be used in lapidary or jewelry.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Milky quartz gets its appearance from tiny fluid inclusions of gas or liquid trapped during crystal growth.

Field identification & locations

Identified in the field by its hardness (scratches glass), lack of cleavage, and white opaque color. Very common in riverbeds and glacial till throughout North America and Europe.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral