Cacholong
![Cacholong, in the Geological Museum of Kiev University](/Images/godic/202501/02/Cacholong0324.jpg")
Cacholong, also known as Kalmuck Agate, is a form of common opal, although it is often mistaken for agate or chalcedony. A milky white colour with a Mohs hardness of about 6, it is used for carving, cameos, etc. Found in Austria, Czech Republic, Mongolia and Uzbekistan, its name possibly comes from a river in Uzbekistan.