Calcite on Matrix
Calcite (Calcium Carbonate) · Mineral Specimen
Crystal System
Trigonal; this specimen exhibits a botryoidal/globular growth habit and a microcrystalline druzy coating on a massive matrix.
Mineral Group
Carbonates (Calcite Group)
Chemical Formula
CaCO3
Formation Process
Sedimentary or Hydrothermal; formed through the precipitation of calcium carbonate from aqueous solutions, often in low-temperature environments or as secondary coatings in rock cavities.
About This Crystal
White, opaque to translucent globular growth of calcite sitting atop a dark, iron-stained rocky matrix. The specimen shows a dull to vitreous luster with a finely crystalline surface texture in the lighter regions.
Physical Characteristics
Color: White/Cream; Streak: White; Cleavage: Perfect rhombohedral (not visible in this habit); Fracture: Conchoidal; Specific Gravity: 2.71; Fluorescence: Often fluoresces red or pink under UV light.
Optical Properties
Refractive Index: 1.486 - 1.658; Birefringence: Extremely high (0.172); Uniaxial negative; no significant pleochroism in this form.
Hardness & Durability
Origin Region
Worldwide distribution; common in karst regions, hydrothermal veins, and sedimentary basins like those found in the UK, USA, and Mexico.
Hardness & Durability
Mohs Hardness: 3; Brittle; low durability; easily scratched by metal or harder minerals; highly sensitive to acids.
Care & Maintenance
Clean only with warm, soapy water; avoid all acids (including vinegar) and ultrasonic cleaners. Store separately from harder gemstones to prevent scratching.
Rarity & Value
Common; value for this specific specimen is low, primarily as a field-collected mineral sample or educational specimen.
Special Characteristics
Strong effervescence when exposed to cold dilute hydrochloric acid; potential for phosphorescence or fluorescence under UV light.
Lore & History
Historically used as a flux in smelting and in the production of lime. In lore, white calcite is associated with the Crown Chakra and believed to be a powerful amplifier and cleanser of energy.