Gray Quartzite
Quartzite (Metamorphic rock predominantly composed of Quartz) · Mineral Specimen / Decorative Stone
Crystal System
Trigonal (individual grains); Massive/Granular habit for the rock specimen
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 (Silicon Dioxide) with trace Al, Fe, and Mg
Formation Process
Metamorphic; forms from the recrystallization of quartz sandstone under high heat and pressure (regional metamorphism)
About This Crystal
Opaque to translucent gray stone with a sugary, granular texture. Displays a dull to greasy luster on unpolished surfaces with visible interlocking grains.
Physical Characteristics
Color: Light to medium gray; Streak: White; Cleavage: None (grains are interlocking); Fracture: Conchoidal to uneven; Specific Gravity: 2.63-2.67; Fluorescence: Usually none
Optical Properties
Refractive Index: ~1.544-1.553; Birefringence: 0.009; No pleochroism or special optical phenomena in massive form
Hardness & Durability
Origin Region
Globally abundant; notable deposits in Brazil, USA (Appalachians), and Scandinavia within metamorphic belts
Hardness & Durability
Mohs Hardness: 7; Very high toughness due to interlocking grain structure; Excellent stability against chemicals and light
Care & Maintenance
Extremely durable; safe to clean with warm soapy water and soft brushes; can withstand ultrasonic cleaners; avoid dropping on harder surfaces to prevent chipping
Rarity & Value
Very Common; low commercial value for rough specimens; primarily valued for industrial use or architectural slabs
Special Characteristics
Displays a characteristic 'sugary' sparkle on fractured surfaces where light reflects off individual quartz grain facets
Lore & History
Historically used for making stone tools due to its hardness. In modern folklore, it is associated with stability, grounding, and the transformation of energy.