Carnelian (Chalcedony)

Physical Properties

Hardness: 6.5-7.0 (Mohs scale); Color: Translucent reddish-orange to brownish-red; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.64.

Formation & Geological History

Formed from the precipitation of silica in volcanic and sedimentary environments, often filling cavities in rocks. The red color is caused by the presence of iron oxide (hematite) impurities throughout the cryptocrystalline quartz structure.

Uses & Applications

Primarily used in jewelry making (beads, cabochons), lapidary art, and as a semi-precious collector's stone. Historically used for signet rings and amulets.

Geological Facts

Carnelian was highly prized in Ancient Egypt, where it was thought to assist spirits in their journey to the afterlife. It is a birthstone for the zodiac sign Virgo.

Field Identification & Locations

Identify in the field by its waxy luster, orange hue, and lack of visible crystal grains. Often found as rounded pebbles in riverbeds or within basaltic geodes. Common locations include Brazil, India, Uruguay, and Madagascar.

Identified on: 4/25/2026

Mode: Standard