mineral
Chalcedony with Quartz Crystals
Silicon Dioxide (SiO2)
Hardness: 6.5-7 Mohs; Color: Grayish-blue base with white to translucent crystals; Luster: Waxy to vitreous; Crystal Structure: Trigonal/Microcrystalline; Cleavage: None; Conchoidal fracture.
- Hardness
- 6
- Color
- Grayish-blue base with white to translucent crystals
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 Mohs; Color: Grayish-blue base with white to translucent crystals; Luster: Waxy to vitreous; Crystal Structure: Trigonal/Microcrystalline; Cleavage: None; Conchoidal fracture.
Formation & geological history
Formed by the deposition of silica-rich fluids in cavities (vugs) within volcanic or sedimentary rocks. The outer layer is chalcedony, while the interior geode-like growth consists of macrocrystalline quartz.
Uses & applications
Used primarily for aesthetic collecting, meditation, jewelry cabochons, and as a decorative stone in metaphysical practices.
Geological facts
It is a member of the quartz family. Grey chalcedony is specifically known as 'blue chalcedony' when it has a more saturated hue. This specimen appears to be a fragment of a small geode or nodule.
Field identification & locations
Identify by its waxy luster on the base and the presence of small, sparkling drusy quartz crystals on the surface. Commonly found in basaltic lava cavities or weathered limestone.
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