Carnelian
Quartz var. Carnelian · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal/Hexagonal; microcrystalline (cryptocrystalline) structure featuring a massive or water-worn pebble habit.
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2 with iron oxide (Fe2O3) impurities
Formation Process
Hydrothermal/Sedimentary; forms when silica-rich fluids permeate cavities in volcanic rocks at relatively low temperatures.
About This Crystal
A translucent to semi-opaque orange-red specimen with a waxy to vitreous luster. This specific piece is a rough, water-worn pebble with a pitted surface and visible dark mineral inclusions.
Physical Characteristics
Color: Orange-red; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.58–2.64; Tenacity: Brittle but tough due to microcrystalline structure.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Pleochroism: None; generally shows a uniform glow when backlit without specific optical phenomena.
Hardness & Durability
Origin Region
Major sources include Brazil, Uruguay, India, and Madagascar; typically found in volcanic cavities (geodes) or as weathered alluvial pebbles.
Hardness & Durability
Mohs hardness: 6.5 to 7. Good durability for jewelry use; resistant to scratches from most household objects but can be chipped by harder materials.
Care & Maintenance
Safe to clean with warm soapy water and a soft brush. Avoid prolonged exposure to intense heat which may alter the iron oxidation state and color.
Rarity & Value
Common; value is determined by color intensity (deep red-orange being preferred) and translucency. Large, clear pieces are more valuable.
Special Characteristics
Subject to color enhancement through heat treatment; often exhibits 'water-skin' or desert varnish on rough surfaces when found in alluvial deposits.
Lore & History
Historically used in Ancient Egypt for amulets and in Roman signet rings. Traditionally associated with the Sacral Chakra, representing courage, vitality, and motivation.