CHALCEDONY ⬇️ Chalcedony is a cryptocrystalline variety of silica (SiO₂), composed of extremely fine intergrowths of quartz and moganite. It typically forms in massive, botryoidal, or stalactitic habits and is known for its waxy lustre and smooth, often translucent appearance. Chalcedony occurs in a wide range of colours, including white, grey, blue, and brown, depending on the presence of impurities. It forms in low-temperature environments such as volcanic cavities and sedimentary rocks. Commo