Blue Calcite
Calcite var. Blue · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically occurs in massive form or rhombohedral crystals with perfect rhombohedral cleavage.
Mineral Group
Carbonates (Calcite Group)
Chemical Formula
CaCO3 (Calcium Carbonate)
Formation Process
Sedimentary or Metamorphic; formed through chemical precipitation in marine environments or hydrothermal veins.
About This Crystal
Soft sky-blue to grayish-blue coloration with a waxy to vitreous luster. This specimen is translucent to opaque with visible cleavage planes and some iron/oxide staining on the lower half.
Physical Characteristics
Color: Pale blue; Streak: White; Cleavage: Perfect rhombohedral in three directions; Fracture: Conchoidal; Density: 2.71; Fluorescence: Often fluoresces pink or red under SW UV.
Optical Properties
Refractive Index: 1.486 - 1.658; Birefringence: Extremely high (0.172); Uniaxial negative; no significant pleochroism.
Hardness & Durability
Origin Region
Madagascar and Mexico are the primary sources of high-quality sky-blue Calcite.
Hardness & Durability
Mohs Hardness: 3. Very soft and brittle; unsuitable for rings. Easily scratched by a copper coin or steel knife.
Care & Maintenance
Handle with extreme care. Keep away from acids (including vinegar) which cause it to effervesce and dissolve. Clean only with warm soapy water; avoid ultrasonic cleaners.
Rarity & Value
Common and affordable. Value is determined by color intensity and the absence of distracting inclusions or internal fractures.
Special Characteristics
Double refraction (calcite can show double images of text placed beneath a clear sample); notable for its characteristic 'waxy' soapy feel to the touch.
Lore & History
Historically used in various cultures as a decorative stone. In metaphysical traditions, it is associated with the throat chakra, believed to aid communication, soothe anxiety, and promote emotional healing.