sedimentary
Blue Agate (Dyed Chalcedony)
Silicon Dioxide (SiO2)
Hardness: 6.5-7 on the Mohs scale; Color: Vibrant blue (artificially dyed); Luster: Vitreous to waxy; Crystal structure: Microcrystalline quartz (cryptocrystalline); Cleavage: None, exhibits conchoidal fracture; Specific gravity: 2.60-2.65.
- Hardness
- 6
- Color
- Vibrant blue (artificially dyed)
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 on the Mohs scale; Color: Vibrant blue (artificially dyed); Luster: Vitreous to waxy; Crystal structure: Microcrystalline quartz (cryptocrystalline); Cleavage: None, exhibits conchoidal fracture; Specific gravity: 2.60-2.65.
Formation & geological history
Forms in cavities of volcanic and metamorphic rocks through the slow deposition of silica-rich groundwater over millions of years. The vibrant blue color is typically the result of post-extraction laboratory dyeing to enhance aesthetic appeal.
Uses & applications
Commonly used in lapidary arts, wire-wrapping, metaphysical crystal collections, and affordable fashion jewelry.
Geological facts
While naturally occurring blue chalcedony exists (such as chrysoprase or gem silica), intense uniform blue colors like this specimen are almost universally achieved by soaking grey or white agate in a dye solution, a practice dating back to Roman times.
Field identification & locations
Can be identified in hand specimen by its characteristic conchoidal (shell-like) fracture and waxy luster, though unnatural color concentration in micro-fractures often reveals human processing. Found globally where chalcedony deposits occur, prominently Brazil, India, and Madagascar.
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