05/31/2026
Chalcedony[a] is an aggregate of cryptocrystalline or microcrystalline silica, or in simpler terms, a mass of individual silica crystals that are too small to be seen without magnification. It is composed primarily of quartz, with minor amounts of intergrown moganite.These are both silica minerals with a chemical composition of SiO2, but they differ in that quartz has a more symmetrical crystal structure (trigonal) than moganite (monoclinic). Mineralogically speaking, the quartz and moganite crystals in chalcedony must grow in parallel chains, called "fibers." However, the term chalcedony may more broadly refer to any microcrystalline or cryptocrystalline silica, fibrous or not. Open May 31st from 11am until 4pm.