sedimentary
Druzy Quartz on Sandstone
Silicon Dioxide (SiO2) with Quartz Crystals on Clastic Sedimentary Rock
Hardness: 7 (quartz crystals) on Mohs scale; Color: Tan, brown, and grey with sparkling clear/white crystals; Luster: Vitreous/sparkly (crystals) to earthy (matrix); Structure: Hexagonal crystals on a granular matrix; Specific Gravity: Approx 2.65
- Hardness
- 7 (quartz crystals) on Mohs scale
- Color
- Tan, brown, and grey with sparkling clear/white crystals
- Luster
- Vitreous/sparkly (crystals) to earthy (matrix)
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Physical properties
Hardness: 7 (quartz crystals) on Mohs scale; Color: Tan, brown, and grey with sparkling clear/white crystals; Luster: Vitreous/sparkly (crystals) to earthy (matrix); Structure: Hexagonal crystals on a granular matrix; Specific Gravity: Approx 2.65
Formation & geological history
Formed through the deposition of sand grains (sedimentary process) followed by hydrothermal activity or mineral-rich groundwater filling vugs and fractures, precipitating a 'druse' layer of tiny quartz crystals over millions of years.
Uses & applications
Primarily used as decorative specimens, for educational geology collections, and sometimes in metaphysical practices. The host rock (sandstone) is widely used in construction.
Geological facts
The term 'druzy' refers to a coating of fine crystals on a rock surface. These sparkling layers take thousands of years to grow as silica-saturated water slowly evaporates or cools within rock cavities.
Field identification & locations
Identify by looking for a 'sugar-like' sparkle on a rough, grainy rock surface. Often found in areas with sedimentary basin histories. Collectors value specimens with high luster and unbroken crystal coverage.
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