Amazonite
Microcline var. Amazonite · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Triclinic; typically occurs as large, well-formed prismatic crystals or massive, cleavable aggregates. Crystals often show Baveno, Manebach, or Carlsbad twinning.
Mineral Group
Silicates (Tectosilicate subgroup); Alkali Feldspar group within the Microcline series.
Chemical Formula
K(AlSi3O8) with trace amounts of Lead (Pb) or Divalent Iron (Fe2+) which provide the turquoise color.
Formation Process
Igneous formation; specifically crystallized from late-stage cooling of granitic pegmatites or occasionally in hydrothermal veins. The specific blue-green color requires the presence of lead and water inside the crystal lattice over long geological timescales.
About This Crystal
A light green to turquoise-blue variety of microcline feldspar. This specimen is opaque to translucent with a vitreous to pearly luster. It exhibits a blocky, cleavable habit with characteristic white streaks (perthitic lamellae) across the surface caused by the exsolution of albite.
Physical Characteristics
Color: Pale green to intense blue-green; Streak: White; Cleavage: Perfect in two directions meeting at nearly 90 degrees; Fracture: Uneven to sub-conchoidal; Specific Gravity: 2.56-2.58; Fluorescence: Weak olive-green or tan under UV light.
Optical Properties
Refractive Index: 1.522-1.530; Birefringence: 0.008; Optically Biaxial (-); Displays a characteristic 'perthitic' texture visible as fine white lines or mottling due to intergrowths of different feldspars.
Hardness & Durability
Origin Region
Prominent sources include the Pikes Peak and Teller County regions of Colorado (USA), Minas Gerais (Brazil), Madagascar, and the Ilmen Mountains (Russia). It typically forms in granitic pegmatites.
Hardness & Durability
Mohs Hardness: 6.0 to 6.5; Toughness: Poor to Fair due to perfect cleavage. It is brittle and can split easily if struck or subjected to pressure, making it moderately durable for jewelry.
Care & Maintenance
Clean with warm, soapy water and a soft cloth; avoid ultrasonic cleaners and steam cleaners. Amazonite is sensitive to rapid temperature changes and harsh chemicals. It can fade if exposed to prolonged intense sunlight over many years.
Rarity & Value
Relatively common but high-quality, deep-saturated blue-green specimens with sharp crystal faces are rare and highly valued by collectors. Treatments are rare, though some material may be resin-stabilized or dyed.
Special Characteristics
Displays 'schiller' or a pearly sheen on cleavage planes; characterized by the presence of white perthitic mottling which distinguishes it from green jade or aventurine.
Lore & History
Historically used in Ancient Egypt for jewelry and amulets (found in Tutankhamun's tomb). Named after the Amazon River, though it is not naturally found there. Traditionally known as the 'Stone of Hope,' associated with the Heart and Throat chakras in crystal healing practices.