Calcite Geode with Pyrite Matrix
Calcite var. Honey Calcite on Pyrite · Mineral Specimen
Crystal System
Trigonal (Calcite), Cubic (Pyrite)
Mineral Group
Carbonates (Calcite), Sulfides (Pyrite)
Chemical Formula
CaCO3 (Calcite) / FeS2 (Pyrite)
Formation Process
Hydrothermal and sedimentary precipitation within cavities, where mineral-rich fluids fill empty spaces to form geodes
About This Crystal
A geode specimen featuring an outer crust embedded in a matrix of crystalline pyrite, with a hollow interior lined with translucent amber to honey-colored scalenohedral calcite crystals displaying vitreous luster
Physical Characteristics
Honey yellow to brown calcite crystals with white rhombohedral layers, metallic brassy-yellow pyrite matrix, white streak, perfect rhombohedral cleavage for calcite, conchoidal to uneven fracture, specific gravity around 2.71 for calcite and 5.0 for pyrite, brittle tenacity, may fluoresce pink or orange under UV light
Optical Properties
Uniaxial negative for calcite with strong birefringence (double refraction), transparent to translucent crystal faces, vitreous luster
Hardness & Durability
Origin Region
Commonly found in Morocco, Peru, China, and the USA; forms in sedimentary and hydrothermal environments
Hardness & Durability
Mohs hardness of 3 for calcite and 6 to 6.5 for pyrite; calcite is soft, scratches easily with a copper coin, and has perfect cleavage making it vulnerable to impacts; unsuitable for everyday jewelry
Care & Maintenance
Clean with a soft, damp cloth; avoid harsh chemical cleaners, acids, and prolonged exposure to direct sunlight; do not submerge in water for extended periods due to calcite's water solubility
Rarity & Value
Common to uncommon depending on size, aesthetics, and crystal perfection; prices range from accessible to moderately expensive for large, pristine geode clusters
Special Characteristics
Displays distinct scalenohedral crystal habit (dogtooth spar), strong double refraction in transparent varieties, and an interesting combination of a carbonate crystal lining inside a metallic sulfide matrix
Lore & History
Calcite has historically been used for its optical properties (Iceland spar in navigation and science) and is traditionally associated in crystal healing with energy amplification, grounding, and clearing negative energy, though these are cultural beliefs and not scientifically proven