mineral

Agate (Carnelian type)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 Mohs; Color: reddish-orange, brown, white; Luster: waxy to vitreous; Crystal structure: Trigonal (cryptocrystalline); Cleavage: none; Specific gravity: 2.58-2.64.

Hardness: 6
Color: reddish-orange, brown, white
Luster: waxy to vitreous

Identified June 28, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: reddish-orange, brown, white; Luster: waxy to vitreous; Crystal structure: Trigonal (cryptocrystalline); 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. This specimen shows a banded, chalcedony-rich structure typical of secondary mineral filling in volcanic vesicles.

Uses & applications

Used primarily for semi-precious jewelry (beads, cabochons), ornamental carvings, and by mineral collectors. Historically used for making mortar and pestles due to its hardness.

Geological facts

Agate is named after the Achates River in Sicily. The reddish hue in this carnelian-like specimen is caused by iron oxide impurities. It has been used for signet rings and protective amulets since the Neolithic era.

Field identification & locations

Identify in the field by its translucent edges, waxy appearance when broken, and lack of cleavage. Common in volcanic regions or riverbeds. Collectors look for unique banding patterns or 'eyes'.