Carnelian Agate
Quartz var. Chalcedony var. Carnelian · Semi-Precious Gemstone and Mineral Specimen
Crystal System
Trigonal, microcrystalline cryptocrystalline quartz forming massive, nodular, or botryoidal habits
Mineral Group
Silicates, subgroup Tectosilicates
Chemical Formula
SiO2
Formation Process
Hydrothermal and sedimentary processes involving the deposition of silica-rich groundwater inside cavities and fractures at low temperatures and pressures
About This Crystal
The specimen shows a brownish-orange to translucent reddish-brown coloration characteristic of carnelian combined with translucent chalcedony or quartz crystal areas, exhibiting a waxy to vitreous luster
Physical Characteristics
Color ranges from orange, reddish-orange to brownish-red; streak is white; cleavage is none; fracture is conchoidal to uneven; specific gravity is approximately 2.60 to 2.65; tenacity is brittle
Optical Properties
Refractive index ranges from 1.530 to 1.540; doubly refractive with a microcrystalline aggregate structure; typically translucent to semi-transparent with no significant pleochroism
Hardness & Durability
Origin Region
Found globally with notable sources in Brazil, India, Madagascar, Uruguay, and the United States, typically within volcanic or sedimentary rock cavities
Hardness & Durability
Mohs hardness of 6.5 to 7; good toughness and durability making it suitable for various types of jewelry wear without easily scratching
Care & Maintenance
Can be safely cleaned with warm soapy water and a soft brush; avoid harsh chemicals, prolonged exposure to direct sunlight to prevent potential color alterations, and store separately from harder gems
Rarity & Value
Common to uncommon depending on color saturation and translucency; affordable and widely accessible, with high-transparency or deeply saturated pieces commanding higher values; heat treatment to enhance color is historically common
Special Characteristics
Displays distinctive banding or color zoning typical of chalcedony varieties, with iron oxide impurities imparting the warm orange and red tones
Lore & History
Historically used by ancient civilizations including the Egyptians, Romans, and Greeks for signet rings, talismans, and royal jewelry; traditionally associated with courage, vitality, motivation, and the lower chakras in crystal healing lore