Feldspar (Sunstone/Moonstone variety)
Feldspar group mineral (likely Orthoclase or Oligoclase) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Monoclinic or Triclinic; Habit: Massive to Tabular; displaying distinct cleavage planes.
Mineral Group
Silicates; Tectosilicates (Framework Silicates)
Chemical Formula
(K,Na,Ca)(Al,Si)4O8
Formation Process
Igneous formation; crystallized from cooling magma in pegmatites or metamorphic environments.
About This Crystal
The specimen shows a rough, rocky matrix with a high-luster cleavage face. It displays a white to silvery sheen (adularescence) or schiller effect, appearing translucent to opaque with a vitreous to pearly luster on fresh surfaces.
Physical Characteristics
Color: White, grey, or tan; Streak: White; Cleavage: Two directions at nearly 90 degrees; Fracture: Uneven to conchoidal; Specific Gravity: 2.55-2.63; Fluorescence: Weak red or orange under UV.
Optical Properties
Refractive Index: 1.518-1.526; Birefringence: 0.005-0.008; Displays adularescence or aventurescence depending on internal inclusions like goethite or hematite plates.
Hardness & Durability
Origin Region
Commonly found in Norway, India, Canada (Labrador), and USA (Oregon). Found in plutonic igneous rocks and pegmatites.
Hardness & Durability
Mohs Hardness: 6.0 to 6.5; Brittle tenacity; fair durability but prone to cracking along cleavage planes if struck.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaning due to cleavage risks. Store separately to avoid scratching.
Rarity & Value
Common mineral group, but gem-quality specimens with strong optical effects are uncommon and moderately valued based on the intensity of the 'shiller'.
Special Characteristics
Schiller effect: a metallic-looking luster resulting from light reflecting off tiny plate-like inclusions or internal lamellar structures.
Lore & History
Historically used in various cultures as a stone of protection or luck; Feldspars represent the most abundant mineral group in Earth's crust. Metaphysically associated with the Solar Plexus chakra and believed to instill vitality.