mineral

Carnelian Agate Nodule

Silicon Dioxide (SiO2) - Carnelian Chalcedony

Hardness: 6.5-7 (Mohs); Color: Waxy reddish-orange, brown, and tan; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); SG: 2.58-2.64

Hardness: 6
Color: Waxy reddish-orange, brown, and tan
Luster: Vitreous to waxy

Identified May 11, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Waxy reddish-orange, brown, and tan; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); SG: 2.58-2.64

Formation & geological history

Formed in volcanic host rock cavities (vesicles) where silica-rich fluids deposited layers over time. Known examples are often from Tertiary age deposits.

Uses & applications

Used primarily in lapidary work for cabochons, beads, jewelry, and as decorative display specimens for collectors.

Geological facts

Carnelian has been used as a gemstone since the Bronze Age. The reddish tint comes from iron oxide impurities. This specific nodule shows the typical 'pit' texture on the exterior common in river-worn or weathered agates.

Field identification & locations

Identify in the field by its waxy luster, translucency when held to light, and superior hardness (it will scratch glass). Commonly found in river beds, beaches, and volcanic regions like Oregon or Brazil.

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sedimentary

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Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

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mineral