Blue Moss Agate / Blue Chalcedony

Physical Properties

Hardness: 6.5–7 on the Mohs scale; Color: Translucent blue, teal, or greenish-blue with internal inclusions; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58–2.64

Formation & Geological History

Formed through the deposition of silica from groundwater in the cavities of igneous rocks such as basalt. The blue hue is often due to the Tyndall effect (scattering of light) or trace mineral inclusions like celadonite or chlorite.

Uses & Applications

Primarily used in jewelry (cabochons, beads), decorative carvings, and as a collector's stone. It is also highly popular in the metaphysical and lapidary communities.

Geological Facts

While often called 'Moss Agate' due to the dendritic or branch-like inclusions visible inside, this specific blue variety is often sought after for its calming oceanic color. Agates have been used as amulets and ornaments since the Neolithic era.

Field Identification & Locations

Identify in the field by its conchoidal fracture, waxy luster when broken, and relative hardness (it will scratch glass). Commonly found in volcanic regions of India, Brazil, Uruguay, and the United States (Oregon/Montana).

Identified on: 4/13/2026

Mode: Standard