Druzy Quartz on Matrix
Quartz (IMA approved), variety: Druzy/Crystalline · Mineral Specimen / Decorative Stone
Crystal System
Trigonal; typically occurs here as a druzy coating of small, sub-millimeter hexagonal prisms with rhombohedral terminations.
Mineral Group
Silicates; Tectosilicate subgroup
Chemical Formula
SiO2 (Silicon Dioxide)
Formation Process
Hydrothermal; formed by the precipitation of silica-rich fluids in rock cavities or fractures at relatively low temperatures.
About This Crystal
A dense coating of tiny, sparkling clear-to-greyish crystals (druzy) over a darker, possibly basaltic or sedimentary matrix. Exhibits a vitreous luster and translucent to transparent clarity in individual crystals, creating a 'glitter' effect.
Physical Characteristics
Color: Colorless to greyish-black; Streak: White; Cleavage: None; Fracture: Conchoidal (observable on matrix breakdown); Specific Gravity: 2.65; Fluorescence: Generally inert but can vary based on trace impurities.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Doubly refractive; Individual crystals are too small to exhibit macroscopic pleochroism.
Hardness & Durability
Origin Region
Global; common in regions like Brazil, Morocco, and the USA (notably Missouri and Utah), often found in volcanic vugs or sedimentary geodes.
Hardness & Durability
Mohs Hardness: 7; Toughness: Brittle; Highly durable for display, though the druzy points can be prone to chipping if knocked against harder surfaces.
Care & Maintenance
Safe to clean with warm soapy water and a soft brush. Avoid ultrasonic cleaners as they may vibrate the tiny crystals loose from the matrix. Keep away from hydrofluoric acid.
Rarity & Value
Common; Value is determined by the aesthetics of the sparkles, the color of the underlying matrix, and the size of the specimen. Generally affordable.
Special Characteristics
The primary feature is the 'druzy' effect—a carpet of micro-crystals that catch light from multiple angles, sometimes exhibiting many small 'rainbows' due to light interference.
Lore & History
Quartz has been used since antiquity for tools and talismans. In metaphysical traditions, druzy quartz is believed to amplify the properties of the stone it coats and is associated with 'spiritual harmony' and the Crown Chakra.