Chalcedony (Moonstone-like Agate)

Physical Properties

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.

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.

Identified on: 4/19/2026

Mode: Standard