1.9" Colorless Apophyllite Crystal Cluster with Chalcedony - India

This specimen comes from the Deccan Traps (a large igneous province and one of the largest volcanic features on earth) in the Pune Province of India. In the course of quarrying for other materials or digging wells sometimes large pockets of zeolites and other minerals are unearthed in the volcanic rock.

Apophyllite while not a zeolite itself is almost always found associated with zeolites in the same pockets. It has two crystal habits, a rectangular prism capped by a steep four sided pyramid or a pseudo-cubic structure. While not a well known mineral to the general public it is popular among mineral collectors due to it's pastel colors and beautiful crystal formations.

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.