mineral

Yellow Quartz (Chert/Chalcedony)

Silicon Dioxide (SiO2) with iron inclusions

Hardness: 7 on Mohs scale; Color: Yellow-brown to tan; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Hardness: 7 on Mohs scale
Color: Yellow-brown to tan
Luster: Waxy to vitreous

Identified June 7, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Yellow-brown to tan; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Formation & geological history

Formed through the accumulation of silica-rich fluids in sedimentary environments or as secondary fillings in vesicles. Often weathered into smooth pebbles by water action.

Uses & applications

Used in landscaping, tumble polishing for hobbyists, and occasionally for lapidary work or as flint for fire-starting.

Geological facts

This specimen shows the characteristic waxy luster of cryptocrystalline quartz. It is often referred to as 'river chert' when found in alluvial deposits. Iron oxides give it the yellow or brownish tint.

Field identification & locations

Look for a smooth, waxy feel and the inability to be scratched by a steel knife. Common in riverbeds, glacial tills, and desert pavements worldwide.

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