Blue Celestite
Celestine (IMA-approved name); variety: Blue Celestine · Collector Mineral and Semi-Precious Gemstone (though rarely faceted due to softness).
Crystal System
Orthorhombic crystal system; typically occurs in tabular or prismatic crystals, but commonly found as grainy, massive, or as geodes containing delicate bladed crystals.
Mineral Group
Sulfates; specifically belonging to the Baryte group.
Chemical Formula
SrSO4 (Strontium Sulfate)
Formation Process
Primarily Sedimentary, often forming in evaporite deposits or as a diagenetic mineral in limestones and dolomites. Can also occur in hydrothermal veins and occasionally in volcanic geodes.
About This Crystal
The specimen displays a pale to sky-blue color with a vitreous to pearly luster. It is translucent to opaque in its massive form, exhibiting a grainy, crystalline texture with visible fracture planes characteristic of sulfate minerals.
Physical Characteristics
Color: Sky blue; Streak: White; Cleavage: Perfect on {001} and good on {210}; Fracture: Uneven to conchoidal; Specific Gravity: 3.9–4.0; Fluorescence: Often fluoresces yellow or blue under UV light.
Optical Properties
Refractive Index: 1.622–1.635; Birefringence: 0.009 (low); Pleochroism: Weak (shades of blue); Optically biaxial positive.
Hardness & Durability
Origin Region
Madagascar is the primary source for the high-quality sky-blue geodes; also found in Sicily (Italy), Sakoany, and various parts of the USA (Ohio, Michigan).
Hardness & Durability
Mohs hardness: 3.0 to 3.5. Very low durability; brittle tenacity and perfect cleavage make it highly susceptible to breakage and scratching.
Care & Maintenance
Clean only with a soft, dry cloth or lukewarm soapy water with extreme care. Avoid ultrasonic cleaners, steam, and harsh chemicals. Store in a dark place as the blue color can fade in prolonged direct sunlight.
Rarity & Value
Common as a mineral specimen but high-quality blue crystals are highly sought after. Value is determined by color intensity and crystal size. Geodes from Madagascar are the standard commercial variety.
Special Characteristics
Known for its 'celestial' blue color and high strontium content (which is used in fireworks for red flames); occasionally shows zoning or phantom growth patterns.
Lore & History
Named from the Latin 'caelestis' (celestial/heavenly) in reference to its color. In traditional lore, it is associated with communication, peacefulness, and the throat chakra. Historically significant as an ore of strontium.