Pearl (Freshwater)
Calcium Carbonate var. Cultured Freshwater Pearl · Organic Gemstone
Crystal System
Amorphous or Orthorhombic (Microcrystalline Argonite), typically occurring in a star-shaped mollusk-beaded form
Mineral Group
Carbonates (Aragonite/Calcite group)
Chemical Formula
CaCO3 with organic protein (conchiolin) and H2O
Formation Process
Biogenic; formed within freshwater mollusks (Unionidae) through the secretion of nacre over a star-shaped mantle tissue or bead nucleus
About This Crystal
A star-shaped bead with a creamy white body color and strong pearly luster. It exhibits a visible 'orient' (iridescence) and characteristic surface ripples or 'nacre ripples' common in freshwater culturing. The transparency is opaque.
Physical Characteristics
Color: White to cream with pinkish overtones; Streak: White; Cleavage: None; Fracture: Uneven; Specific Gravity: 2.60-2.85; Fluorescence: Often weak yellow-white under LWUV
Optical Properties
Refractive Index: 1.530-1.685; Birefringence: 0.155 (usually not measurable in nacre); Phenomenon: Orient (iridescence caused by interference and diffraction of light at the plate edges)
Hardness & Durability
Origin Region
Primarily China (Lake Tai and similar regions), Japan, and South East Asia in freshwater mussels
Hardness & Durability
Mohs Hardness: 2.5 - 4.5; Toughness: Usually good but vulnerable to crushing or dehydration; Stability: Poor (sensitive to acids, perspiration, and heat)
Care & Maintenance
Clean with a soft damp cloth only; avoid all chemicals (perfumes, hairspray), ultrasonic cleaners, and steam; store separately in a soft pouch to prevent scratches
Rarity & Value
Common (for freshwater varieties); Value factors: Luster, surface quality, and symmetry of the star shape; treatments: bleaching and polishing are standard
Special Characteristics
Orient (iridescence), star-shaped nucleated growth, and sub-metallic to pearly luster
Lore & History
Historically known as 'tears of the gods' in many cultures. Pearls represent purity and wisdom; in crystal healing, they are associated with the Heart and Third Eye chakras and Lunar energy.
Notes
Sold as pearl