mineral

Chalcedony (Botryoidal)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 Mohs; Color: White to pale blue/pink; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.6-2.64

Hardness: 6
Color: White to pale blue/pink
Luster: Waxy to vitreous

Identified June 25, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: White to pale blue/pink; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.6-2.64

Formation & geological history

Formed from the deposition of silica-rich fluids in volcanic cavities (vugs) or sedimentary environments at relatively low temperatures. Often found in geodes or as crusts on other rocks.

Uses & applications

Used in gemstone carving, jewelry (cabochons), and as ornamental display specimens for collectors.

Geological facts

Chaldedony is a cryptocrystalline form of quartz, meaning its crystals are too small to be seen without extreme magnification. The 'bumpy' texture seen here is known as a botryoidal habit, derived from the Greek word for 'bunch of grapes'.

Field identification & locations

Identify by its waxy luster, lack of cleavage, and extreme hardness (it will scratch glass). Commonly found in volcanic regions like Oregon (USA), Brazil, and Iceland.