4.7" Chalcedony Pseudomorph after Calcite - Maharashtra, India

This is a unique, 4.7" wide chalcedony pseudomorph after calcite, collected from Maharashtra, India. This occurred when chalcedony formed/deposited over a cluster of calcite crystals, in this case, rhombohedral calcite. Some of the calcite within the chalcedony has been dissolved away.

Comes with an acrylic display stand.

Chalcedony is any microcrystalline variety of silica composed of very fine intergrowths of quartz and moganite. Microcrystalline meaning the crystals are microscopic and cannot be observed by the naked eye. Both quartz and moganite have the same chemical formula SiO2 (silicon dioxide) but different crystal structures. When free from impurities, chalcedony is colorless and transparent. Dependent on impurities present during formation, chalcedony can form in a wide variety of colors including red, yellow, green, blue, purple, grey, white and numerous color hues in between. Chalcedony is quite hard, being a 7 on the Mohs Hardness Scale, which makes sense considering quartz is the benchmark mineral for a 7.
Quartz var. Chalcedony
Mumbai, Maharashtra, India
4.7 x 3.7"