mineral

Yellow Quartz / Chalcedony

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Yellow to honey-yellow; Luster: Waxy to vitreous; Crystal system: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: ~2.65.

Hardness: 7 on Mohs scale
Color: Yellow to honey-yellow
Luster: Waxy to vitreous

Identified July 23, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Yellow to honey-yellow; Luster: Waxy to vitreous; Crystal system: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: ~2.65.

Formation & geological history

Formed in low-temperature hydrothermal environments or as silica precipitates in cavities and sedimentary deposits. Commonly found in basaltic nodules, river gravels, and arid weathering zones.

Uses & applications

Used primarily for lapidary arts, ornamental carving, gemstone jewelry, and decorative rock collections.

Geological facts

Microcrystalline quartz varieties like chalcedony and jasper have been worked by humans since prehistoric times for tools and amulets due to their hardness and smooth conchoidal fracture.

Field identification & locations

Look for a smooth waxy surface texture, translucent edges when backlit, high hardness (scratches glass), and absence of cleavage planes. Widespread in silica-rich volcanic and sedimentary terranes, including the Horn of Africa rift zones.