mineral

Carnelian Agate

Silicon Dioxide (SiO2) - Variety of Chalcedony

Hardness: 6.5-7 on Mohs scale. Color: Reddish-brown to orange-red. Luster: Waxy to vitreous. Crystal Structure: Hexagonal (cryptocrystalline). Cleavage: None, exhibits conchoidal fracture. Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Reddish-brown to orange-red
Luster: Waxy to vitreous

Identified July 7, 2026More mineral →

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Physical properties

Formation & geological history

Formed in the cavities of volcanic rocks (basalt or rhyolite) through the deposition of silica from groundwater. The red color is due to the presence of iron oxide (hematite) impurities. Often found in riverbeds and beaches as water-worn pebbles.

Uses & applications

Commonly used as a gemstone in jewelry (beads, cabochons), for ornamental carvings, seals, and as a popular collector's specimen.

Geological facts

Carnelian was used by ancient Egyptians and Romans for signet rings and amulets. It was believed to provide courage and protection for the soul in the afterlife. The depth of color is often enhanced by natural solar heat or artificial heating.

Field identification & locations

Identify in the field by its translucent quality, waxy feel, and reddish-orange hue. Its conchoidal fracture (curved, glass-like breaks) is a key identifier. Commonly found in Brazil, India, Uruguay, and parts of the United States.

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Gypsum (variety Selenite or Alabaster)

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Mineral

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Mineral/Rock

Granite

Granite (Phaneritic intrusive igneous rock)

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