Celestite (Celestine) Geode
Celestine (IMA-approved mineral species) · Mineral Specimen / Collector Mineral / Semi-Precious Gemstone
Crystal System
Orthorhombic; typically occurs as dipyramidal or tabular prismatic crystals; often found in geodic or massive habits.
Mineral Group
Sulfates; Baryte group
Chemical Formula
SrSO4 (Strontium Sulfate)
Formation Process
Low-temperature hydrothermal or sedimentary process. Formed the precipitation of strontium-rich fluids in cavities (vugs) within sedimentary rock layers, often during diagenesis.
About This Crystal
A small geode segment featuring translucent to transparent crystals. The crystals exhibit a pale blue to colorless hue with a vitreous (glassy) luster. The interior cavity is lined with well-defined, stubby prismatic terminations against a grayish-white outer host rock matrix.
Physical Characteristics
Color: Pale sky-blue to colorless; Streak: White; Cleavage: Perfect on {001} and good on {210}; Fracture: Conchoidal to uneven; Specific Gravity: 3.95–3.97; Fluorescence: Occasionally shows weak neon-blue or green under shortwave UV.
Optical Properties
Biaxial (+); Refractive Index: 1.622–1.631; Birefringence: 0.009; Pleochroism: Weak (shades of blue); Doubly refractive.
Hardness & Durability
Origin Region
Sakoany Mine, Madagascar (most common source for blue geodes); also found in Sicily, Italy, and Lake Erie, USA. Forms in sedimentary rocks (dolostones and limestones) and hydrothermal veins.
Hardness & Durability
Mohs Hardness: 3 to 3.5. Very brittle and fragile with low toughness. High sensitivity to pressure and thermal shock; unsuitable for most jewelry except protected pendants.
Care & Maintenance
Clean only with room temperature water and mild soap; avoid ultrasonic cleaners and steam. Store in a dark, cool place as the blue color can fade to white or colorless with prolonged exposure to direct sunlight.
Rarity & Value
Common (Madagascar material is abundant); Value is determined by color intensity (deeper blue is better), crystal size, and lack of damage. Small geodes like this are affordable collector pieces ($10-$30).
Special Characteristics
Often exhibits 'perfect' cleavage causing crystals to break along flat planes; noted for its distinct strontium-induced flame (red) if powdered and burned; high density compared to quartz of similar size.
Lore & History
Historically named from the Latin 'caelestis' meaning 'heavenly' or 'celestial' due to its sky-blue color. In traditional crystal healing lore, it is associated with the throat and crown chakras, believed to promote inner peace, mental clarity, and communication with higher realms.