Blue Calcite
Calcite var. Blue · Collector Mineral / Decorative Stone
Crystal System
Trigonal. Commonly occurs in massive, rhombohedral, or crystalline forms; the specimen shown exhibits a massive, somewhat cleavable habit.
Mineral Group
Carbonates (Calcite group). Specific class: Anhydrous carbonate.
Chemical Formula
CaCO3 (Calcium Carbonate). Color often attributed to trace inclusions of other minerals or fluid inclusions.
Formation Process
Sedimentary or Hydrothermal. Primarily forms through chemical precipitation in marine environments or through hydrothermal deposition in limestone cavities at relatively low temperatures.
About This Crystal
A translucent to opaque mass with a distinct waxy to vitreous luster. This specimen displays a pale sky-blue to grayish-blue hue on top with reddish-brown hematite or iron oxide staining on the lower section. It shows characteristic rhombohedral cleavage steps on the surface.
Physical Characteristics
Color: Sky blue; Streak: White; Cleavage: Perfect rhombohedral in three directions; Fracture: Conchoidal (but usually splits along cleavage); Specific Gravity: 2.71; Fluorescence: May show weak pink or orange under UV light.
Optical Properties
Refractive Index: 1.486 to 1.658; Birefringence: Extremely high (0.172); Pleochroism: Weak; Optical Nature: Uniaxial negative.
Hardness & Durability
Origin Region
Madagascar is the primary source; also found in Mexico, South Africa, and the USA (California and New York). Forms in sedimentary environments such as limestone beds.
Hardness & Durability
Mohs Hardness: 3. Very soft and brittle. Easily scratched by a copper coin or steel knife. Not recommended for rings due to low durability.
Care & Maintenance
Clean only with warm soapy water. Do not use ultrasonic or steam cleaners. Highly sensitive to acids (including vinegar/citrus), which will dissolve the stone. Store separately to avoid scratches from harder stones.
Rarity & Value
Common. Generally affordable. Value increases with color saturation and the absence of brown iron staining. Large, deep-blue Madagascar specimens are the most valued.
Special Characteristics
High birefringence (double refraction) is observable in transparent pieces. This specimen demonstrates a characteristic 'waxy' texture and reactive effervescence if in contact with dilute HCl acid.
Lore & History
Traditionally used as a stone for 'calming and communication.' In historical contexts, calcite has been used since antiquity for mortars and Egyptian alabaster-like carvings. Associated with the Throat Chakra in modern crystal healing circles.