mineral

Chalcedony (Moonstone-like Agate)

Silicon Dioxide (SiO₂)

AI-generated identification · may be incorrect

Hardness: 6.5–7 (Mohs scale); Color: Translucent white to milky blue/grey; Luster: Waxy to vitreous; Crystal structure: Trigonal/Monoclinic (Cryptocrystalline); Cleavage: None; Specific Gravity: 2.6–2.64.

Hardness: 6
Color: Translucent white to milky blue/grey
Luster: Waxy to vitreous

Identified April 19, 2026More mineral →

Explore Chalcedony (Moonstone-like Agate) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed from the deposition of silica-rich water in cavities of volcanic and sedimentary rocks. They are often found as water-worn pebbles in stream beds or beaches.

Uses & applications

Used primarily in jewelry (cabochons and beads), as tumbled stones for metaphysical collecting, and historically for seal stones and tools due to its toughness.

Geological facts

Chalcedony is a cryptocrystalline form of silica, meaning its crystals are too small to be seen with a standard microscope. Translucent white specimens are often called 'White Chalcedony' or 'Girasol'.

Field identification & locations

Identify in the field by its translucency, waxy surface texture when wet, and lack of visible grain. Commonly found in gravel pits, riverbeds, and coastal areas with volcanic history.