Chalcedony
Chalcedony forms mostly in rock cavities of various kinds, but mostly in cooling magma, where it forms at low temperatures as a precipitate of silicate solutions. Chalcedony is occasionally encountered as a dehydration product of opal. It can also be found on fractures of serpents, or forms tubers in limestones. Its occurrence is therefore abundant.
Chalcedony is a cryptocrystalline variety of quartz - it is composed of such small crystals that it appears to be solid. It forms smears, crusts, almonds, geodes. It comes in a variety of colors, including blue, gray, white, brown, and pink. It has a fine and silky lustre and a transparent to repetitive surface.
It is also a popular gemstone and is often used in jewellery making. It is often carved into various shapes and used to make necklaces, bracelets, rings and earrings.
