Carnelian (Agate) with Quartz Geode
Quartz (chalcedony variety) var. Carnelian with Macro-crystalline Quartz · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal/Hexagonal; Cryptocrystalline (chalcedony) and small prismatic (druze) habits
Mineral Group
Silicates (Tectosilicates)
Chemical Formula
SiO2 (Silicon Dioxide) with Fe2O3 (Iron Oxide) impurities
Formation Process
Hydrothermal/Secondary: Silica-rich fluids fill cavities in volcanic or sedimentary rocks at low temperatures.
About This Crystal
An orange-to-brownish translucent chalcedony matrix containing a small vug or 'mini-geode' lined with clear to white crystalline quartz druze. The surface shows a waxy to vitreous luster with a slight conchoidally fractured exterior.
Physical Characteristics
Color: Orange, reddish-brown, and white. Streak: White. Cleavage: None. Fracture: Conchoidal. Specific Gravity: 2.58–2.64. Fluorescence: Often inert or weak yellow under UV.
Optical Properties
Refractive Index: 1.544–1.553. Birefringence: 0.009. Pleochroism: None. Optical Phenomenon: Translucency in the carnelian layers.
Hardness & Durability
Origin Region
Commonly sourced from Brazil, India, Madagascar, and Uruguay; found in volcanic basalt and sedimentary environments.
Hardness & Durability
Mohs Hardness: 6.5 to 7. Toughness: Good (carnelian is tougher than macro-crystalline quartz). Highly wearable.
Care & Maintenance
Safe to clean with warm soapy water. Avoid ultrasonic cleaners if fractures are present. Stable in light, though extreme heat may shift color via iron oxidation.
Rarity & Value
Common. Value is determined by color saturation and the presence of aesthetic crystal pockets. Generally inexpensive as a raw specimen.
Special Characteristics
Features a 'druzy' vug (a small cavity lined with crystals) and carnelian color-zoning.
Lore & History
Historically used in Ancient Egypt for amulets and seals. Symbolically associated with the Sacral Chakra, vitality, and courage in traditional lore.