Druzy Quartz on Agate with Jasper
Quartz (Silicon Dioxide) var. Druzy · Mineral Specimen / Semi-Precious Gemstone
Crystal System
Trigonal system; typically displaying a druzy habit consisting of thousands of tiny, sparkling pyramidal crystal terminations.
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2 (Silicon Dioxide) with Fe2O3 (Iron Oxide) inclusions
Formation Process
Hydrothermal/Secondary process: Formed by silica-rich fluids precipitating in rock cavities, often during the cooling of volcanic lavas where gas bubbles create voids.
About This Crystal
A dark basaltic matrix hosting a pocket of sparkling, translucent greyish-white druzy quartz crystals. The druse is bordered by a distinct red layer of jasper and a white band of chalcedony.
Physical Characteristics
Color: Grey-white (crystals), Red (boundary), Dark Grey (matrix); Streak: White; Luster: Vitreous to Adamantine on crystal faces; Fracture: Conchoidal; Density: ~2.65 g/cm³; Fluorescence: Generally inert.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009 (doubly refractive); provides high surface twinkle due to multiple light-reflecting facets (scintillation).
Hardness & Durability
Origin Region
Notable sources include Brazil, Uruguay, and India; often found in volcanic basalt cavities (vugs).
Hardness & Durability
Mohs Hardness: 7; Toughness: Fair to good, though the tiny crystals can be brittle and prone to chipping if struck.
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic cleaners which may dislodge small crystals; store away from harder gems like Topaz or Sapphire.
Rarity & Value
Relatively common; value is determined by the coverage of the crystals, the vibrancy of the surrounding jasper/agate bands, and the overall size of the vug.
Special Characteristics
Displays a 'sugar-coated' effect (druse); contains distinct red jasper banding caused by iron oxide concentrations at the growth interface.
Lore & History
Historically used in jewelry and amulets since ancient Egyptian times. In lore, druzy quartz is believed to amplify the properties of other stones and promote collective harmony.