Opal is gemstone and is the birthstone of October. Composed mainly of silica and water. Commonly found in Australia. There is variety among opal as there different types of opal that can be discovered on Earth. Some examples would be fire opal, girasol opal, and Peruvian opal. The word opal is often said to be deprived from Sanskrit word úpala.
Opal an relatively rare rock composed mainly with silica and also has water