Emerald
Beryl var. Emerald · Precious Gemstone (commercial/low-grade specimen)
Crystal System
Hexagonal; typically forms in elongated prismatic crystals, often with flat terminations; this specimen is tumble-polished and shows a massive or aggregate habit.
Mineral Group
Silicates (Cyclosilicates); member of the Beryl group
Chemical Formula
Be3Al2Si6O18 with Chromium (Cr) and sometimes Vanadium (V) impurities
Formation Process
Metamorphic or Hydrothermal. Forms when hydrothermal fluids containing beryllium react with host rocks containing chromium or vanadium, typically in contact metamorphic zones.
About This Crystal
A tumble-polished, semi-translucent to opaque green stone. It exhibits a mottled appearance with medium to dark green zones mixed with black inclusions (likely mica or schist) and light-to-white internal fractures. The luster is vitreous (glassy) where polished.
Physical Characteristics
Color: Emerald green with black matrix/inclusions. Streak: White. Cleavage: Indistinct on {0001}. Fracture: Conchoidal to uneven. Specific Gravity: 2.67-2.78. Tenacity: Brittle. Fluorescence: Typically inert to weak orangey-red under longwave UV.
Optical Properties
Refractive Index: 1.576-1.582. Birefringence: 0.006. Pleochroism: Distinct (Blue-green to yellow-green). Optical Phenomenon: Doubly refractive; occasionally shows chatoyancy if fibrous inclusions are present (not visible here).
Hardness & Durability
Origin Region
Major sources include Colombia (Muzo, Chivor), Brazil (Minas Gerais), and Zambia; often found in mica schists or hydrothermal veins.
Hardness & Durability
Mohs Hardness: 7.5 to 8.0. Toughness: Poor to Fair (prone to chipping due to internal fractures called 'jardin'). Stability: Sensitive to heat and pressure.
Care & Maintenance
Avoid using ultrasonic or steam cleaners as they may force out oils or shatter the stone. Clean only with warm, soapy water and a soft brush. Keep away from high heat and harsh chemicals.
Rarity & Value
Common (low-grade/commercial grade). High-quality transparent emeralds are extremely rare. Value in this polished tumble form is low ($2-$10). Common treatments include oiling with cedar oil or resins to fill surface-reaching fissures.
Special Characteristics
Features significant internal 'jardin' (garden-like inclusions) and black biotite mica inclusions, which are characteristic of emeralds formed in schist environments.
Lore & History
Historically prized by the Incas and Aztecs; used in Cleopatra’s mines in Egypt. Traditionally associated with the Heart Chakra, it is symbolically linked to rebirth, love, and wisdom in lore dating back to Aristotle and Pliny the Elder.