Rock Identifier
Amber Agate / Carnelian (Chalcedony (Silicon Dioxide, SiO2)) — mineral
mineral

Amber Agate / Carnelian

Chalcedony (Silicon Dioxide, SiO2)

Hardness: 6.5-7 on Mohs scale. Color: Translucent orange, honey-yellow, or brownish-red. Luster: Waxy to vitreous. Crystal Structure: Trigonal (microcrystalline/cryptocrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.58-2.64.

Hardness
6
Color
Translucent orange, honey-yellow, or brownish-red
Luster
Waxy to vitreous
Identified More mineral
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Physical properties

Hardness: 6.5-7 on Mohs scale. Color: Translucent orange, honey-yellow, or brownish-red. Luster: Waxy to vitreous. Crystal Structure: Trigonal (microcrystalline/cryptocrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.58-2.64.

Formation & geological history

Formed through the deposition of silica from groundwater into cavities of igneous rocks, particularly volcanic lavas. Often found as river-worn nodules that have been tumbled naturally over thousands of years.

Uses & applications

Used primarily for lapidary work, jewelry (beads, cabochons), and as aquarium stones or decorative landscaping. High-quality carnelian is prized in carving and seal-making.

Geological facts

Carnelian and amber agate have been used by humans for over 5,000 years; ancient Romans and Egyptians used them for signet rings and amulets because wax does not stick to the smooth surface of the stone.

Field identification & locations

Identify in the field by its translucency when held to a light, its waxy texture, and the absence of visible grains. It is commonly found in gravel pits, riverbeds, and beaches, particularly in the Pacific Northwest (USA) or Brazil.