mineral
Iron-stained quartz pebble
Quartz (SiO₂), likely limonite/goethite-stained
AI-generated identification · may be incorrectHardness 7 Mohs; translucent white to pale gray with rusty-brown iron-oxide patches, vitreous to dull luster, no obvious cleavage, and conchoidal fracture. The rounded shape indicates natural abrasion or tumbling.
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Physical properties
Hardness 7 Mohs; translucent white to pale gray with rusty-brown iron-oxide patches, vitreous to dull luster, no obvious cleavage, and conchoidal fracture. The rounded shape indicates natural abrasion or tumbling.
Formation & geological history
Quartz crystallized from silica-rich igneous or hydrothermal fluids; later weathering deposited iron oxides on fractures and surfaces. Its exact geological age and source cannot be determined from the photograph.
Uses & applications
Common quartz is used in glass, ceramics, abrasives, engineered stone, and electronics; attractive pieces are inexpensive display specimens. It is generally not gem quality.
Geological facts
Rust-colored staining commonly consists of limonite or goethite rather than iron within the quartz crystal lattice. Translucency and the absence of cleavage help distinguish quartz from feldspar.
Field identification & locations
Look for glassy luster, conchoidal fracture, high scratch resistance, and inability to scratch quartz with a steel knife; an unglazed ceramic tile may show a white streak. Quartz pebbles occur widely in stream gravels, soils, and weathered rock deposits.
