Granite / Feldspar with Quartz and Tourmaline
Igneous Rock / Pegmatite Specimen · Mineral Specimen / Rock
Crystal System
Varies by mineral component: Triclinic/Monoclinic (Feldspar), Trigonal (Quartz and Tourmaline)
Mineral Group
Silicates (Tectosilicates and Cyclosilicates)
Chemical Formula
Complex silicate mixture: (K,Na)AlSi3O8 (Feldspar) + SiO2 (Quartz) + complex borosilicate (Tourmaline)
Formation Process
Igneous crystallization from cooling magma or pegmatitic melt deep within the Earth's crust
About This Crystal
A small, rough, whitish-grey rock specimen showing an interlocking crystalline matrix with white feldspar, translucent quartz, and dark patches of accessory minerals such as tourmaline or biotite mica, exhibiting a massive and granular habit with a vitreous to pearly luster.
Physical Characteristics
Color ranges from white and translucent grey to black. Streak is white. Cleavage is good in two directions for feldspar, none for quartz. Fracture is uneven to conchoidal. Specific gravity is approximately 2.6 to 2.7. Tenacity is brittle.
Optical Properties
Displays mixed optical properties due to multiple mineral phases. Feldspars show twinning striations under magnification; quartz is uniaxial positive with single/double refraction depending on the exact crystal orientation.
Hardness & Durability
Origin Region
Worldwide distribution; commonly found in continental shields, mountain ranges, and pegmatite dikes
Hardness & Durability
Mohs hardness is around 6 to 7, driven primarily by the quartz and feldspar components. Durable for general handling but vulnerable to impact due to cleavage planes in feldspar.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid harsh chemical cleaners and ultrasonic cleaners if micro-fractures are present. Store away from softer stones to prevent scratching.
Rarity & Value
Common. Granite and its constituent pegmatitic minerals are abundant globally. Low monetary value for raw hand specimens, primarily valued for educational or decorative purposes.
Special Characteristics
Composed of multiple distinct mineral phases growing together in an interlocking igneous matrix, sometimes exhibiting graphic textures or localized tourmaline crystal growth.
Lore & History
Historically used extensively in architecture, monuments, and sculpture due to its extreme durability. In modern metaphysical practices, granite is associated with grounding, stability, strength, and balancing multiple energies due to its diverse mineral composition.