Feldspar Matrix with Tourmaline and Quartz
Microcline / Feldspar Group Mineral Specimen · Mineral Specimen
Crystal System
Triclinic, massive and blocky habit
Mineral Group
Silicates, Tectosilicate subgroup
Chemical Formula
KAlSi3O8
Formation Process
Igneous pegmatitic crystallization from cooling silicate-rich magma under high volatile pressure
About This Crystal
An irregularly shaped mineral specimen exhibiting a mix of beige, cream, and brownish-yellow tones with crystalline cleavage planes. Dark, near-black patches of accessory minerals, likely tourmaline or biotite, are embedded near the upper edge. The luster varies from vitreous to pearly on cleavage surfaces, with translucent to opaque transparency.
Physical Characteristics
Color ranges from off-white and tan to brownish orange due to iron oxide staining. Streak is white. Shows distinct cleavage in two directions intersecting near 90 degrees. Fracture is uneven to conchoidal. Specific gravity is approximately 2.56. Tenacity is brittle.
Optical Properties
Biaxial optic sign with low birefringence. Displays typical double refraction characteristic of feldspar group minerals, with a refractive index ranging around 1.518 to 1.526.
Hardness & Durability
Origin Region
Worldwide occurrence, commonly found in pegmatites globally including Brazil, Madagascar, and the United States
Hardness & Durability
Mohs hardness of 6. Moderate to poor toughness due to distinct cleavage planes. Sensitive to hydrofluoric acid and thermal shock.
Care & Maintenance
Clean with warm water and mild soap using a soft brush. Avoid harsh chemical cleaners and ultrasonic cleaners due to cleavage planes. Store separately from harder gemstones to prevent scratching.
Rarity & Value
Common, generally valued as a rough educational or display mineral specimen rather than a gemstone, with accessible price points.
Special Characteristics
Contains contrasting dark accessory mineral inclusions set against a weathered feldspar and quartz-rich matrix with visible micro-fractures and iron staining.
Lore & History
In crystal lore, feldspar and associated pegmatite minerals are traditionally used to promote self-discovery, emotional balance, and adaptability to change, though these are cultural beliefs rather than scientifically verified properties.