mineral

Chalcedony Nodule (Carnelian/Agate)

Chalcedony (Silicon Dioxide, SiO2)

Hardness: 6.5–7 on Mohs scale. Color: Translucent amber, honey-brown, or deep orange. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (trigonal) microcrystalline. Cleavage: None (conchoidal fracture). Specific Gravity: 2.6–2.7.

Hardness: 6
Color: Translucent amber, honey-brown, or deep orange
Luster: Vitreous to waxy

Identified February 5, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica-rich groundwater within cavities (vesicles) of volcanic or sedimentary rocks. Over millions of years, the silica precipitates as a gel and crystallizes into microcrystalline quartz.

Uses & applications

Commonly used in lapidary work for making cabochons, beads, and carved jewelry. Also used for ornamental carvings, paperweights, and as a healing stone in metaphysical practices.

Geological facts

Many of these nodules are commonly referred to as 'Cold Water Agates' or 'Lake Superior Agates' depending on the location. If the stone lacks distinct banding, it is classified as chalcedony; if it has bands, it is an agate.

Field identification & locations

Identify in the field by its waxy texture and translucency when held to a light source. Often found in gravel beds, riverbanks, or eroded volcanic regions. Collectors look for high translucency and deep color saturation.

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