Blue Calcite
Calcite var. Blue · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically occurs in massive or rhombohedral habits with perfect rhombohedral cleavage visible on fractured surfaces.
Mineral Group
Carbonates; Calcite Group
Chemical Formula
CaCO3
Formation Process
Sedimentary or Hydrothermal; forms through chemical precipitation in marine environments or through hydrothermal fluids in limestone cavities.
About This Crystal
A soft sky-blue to grayish-blue mineral with a characteristic waxy to vitreous luster. This specimen is translucent with visible internal fractures and distinctive rhombohedral stepped cleavage planes.
Physical Characteristics
Color: Blue; Streak: White; Cleavage: Perfect rhombohedral in three directions; Fracture: Conchoidal to uneven; Specific Gravity: 2.71; Fluorescence: Often shows pink or orange under LWUV.
Optical Properties
Refractive Index: 1.486 - 1.658; Birefringence: Extremely high (0.172); Doubly refractive (may show doubling of text if transparent enough).
Hardness & Durability
Origin Region
Madagascar and Mexico are the primary sources for high-quality blue specimens; also found in sedimentary environments worldwide.
Hardness & Durability
Mohs Hardness: 3; very soft and brittle. Poor durability for jewelry like rings; sensitive to acids (will effervesce in HCl).
Care & Maintenance
Clean only with warm, soapy water; avoid ultrasonic and steam cleaners. Keep away from acids (including vinegar) and harder gemstones to prevent scratching.
Rarity & Value
Common and affordable. Value is determined by the intensity of the blue color and size of the specimen; rarely treated, though occasionally acid-washed for a smoother feel.
Special Characteristics
Displays strong double refraction and perfectly geometric rhombohedral cleavage. Notable for its soothing color and waxy surface texture.
Lore & History
Historically used as a building material and flux; in modern crystal lore, it is associated with the Throat Chakra and believed to aid in calm communication and mental relaxation.