Carnelian
Quartz var. Carnelian (Cryptocrystalline Quartz / Chalcedony) · Semi-Precious Gemstone / Decorative Stone
Crystal System
Trigonal (Hexagonal system); typically occurs in microcrystalline (cryptocrystalline) massive or botryoidal habits rather than distinct crystals.
Mineral Group
Silicates (Tectosilicates / Quartz group)
Chemical Formula
SiO2 (Silicon Dioxide) colored by Hematite impurities (Fe2O3)
Formation Process
Forms via hydrothermal precipitation in volcanic rock cavities (gas bubbles) or as a result of groundwater carrying silica through sedimentary layers at relatively low temperatures.
About This Crystal
A translucent to semi-opaque variety of chalcedony with a waxy to vitreous luster. This specific specimen is orange to reddish-orange with white feathery internal fractures (crazing) and a smooth, tumbled finish.
Physical Characteristics
Color: Orange/Peach; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.58–2.64; Fluorescence: Weak yellow-white or inert under UV light.
Optical Properties
Refractive Index: 1.543–1.554; Double Refraction: Uniaxial (+), though often appears singly refractive due to microcrystalline structure; Pleochroism: None.
Hardness & Durability
Origin Region
Brazil, India (Gujarat), Madagascar, Uruguay, and Botswana; found in volcanic cavities and sedimentary environments.
Hardness & Durability
Mohs Hardness: 6.5–7; Toughness: Excellent (no cleavage); Durability: Very high/suitable for daily wear jewelry.
Care & Maintenance
Wash with warm soapy water and a soft brush. While stable, avoid extreme heat which can alter the iron oxide levels and change its color. Safe for ultrasonic cleaning in most cases.
Rarity & Value
Common; Value is determined by color saturation (deeper reds/oranges are preferred) and translucency. Prices are generally low ($1-$10 for tumbled stones). Heat treatment of lighter chalcedony is common.
Special Characteristics
The color is derived from colloidal iron oxide (hematite). When held to the light, color distribution can appear cloudy or banded (transitioning toward Agate).
Lore & History
Used since the Bronze Age for signet rings and amulets; highly significant in Ancient Egyptian culture (representing the setting sun and fertility) and Islamic tradition (the Prophet Muhammad was said to wear a carnelian seal ring). Traditionally associated with the Sacral Chakra and courage.