Aragonite
Aragonite (variety Sputnik) · Mineral Specimen / Decorative Stone
Crystal System
Orthorhombic. Typically occurring in pseudo-hexagonal cyclic twins forming radiating, acicular, or prismatic clusters.
Mineral Group
Carbonates (Aragonite Group)
Chemical Formula
CaCO3
Formation Process
Sedimentary or Hydrothermal. Formed at low temperatures near the Earth's surface, often in caves as stalactites or via precipitation from hot springs and geysers.
About This Crystal
An orange to reddish-brown cluster of radiating, hexagonal-appearing prismatic crystals. It has a vitreous to resinous luster and ranges from translucent to transparent at the tips.
Physical Characteristics
Color: Orange, reddish-brown, white; Streak: White; Cleavage: Distinct on {010}; Fracture: Subconchoidal; Specific Gravity: 2.95; Fluorescence: Often fluoresces cream or yellow under UV light.
Optical Properties
Biaxial negative; Refractive Index: 1.530–1.685; Birefringence: 0.155 (very high); no significant pleochroism.
Hardness & Durability
Origin Region
Molina de Aragón, Spain (type locality), Morocco, and Mexico. Found in oxidized zones of ore deposits and hot spring deposits.
Hardness & Durability
Mohs Hardness: 3.5 to 4. Low durability; brittle tenacity and sensitive to acids.
Care & Maintenance
Avoid all acids (even vinegar), ultrasonic cleaners, and steam. Clean only with warm soapy water and a soft brush. Store separately to avoid scratching by harder minerals.
Rarity & Value
Common. Value is determined by the symmetry of the 'Sputnik' radial growth and the saturation of the orange color. Generally affordable as collector specimens.
Special Characteristics
Known for cyclic twinning which creates a false hexagonal symmetry ('pseudo-hexagonal'). Distinguishable from calcite by its crystal habit and higher density.
Lore & History
Named in 1797 for the Spanish region of Aragon. In metaphysical traditions, it is considered a 'grounding stone' associated with the Root and Earth Star chakras, believed to aid in patience and reliability.