An opal is considered to be a semi-precious stone. It is a naturally occurring glass.
The gem emblem of South Australia is the opal. The opal was adopted as the state gem on 15 August 1985. Eighty percent of the world's opals come from just three opal mining areas in South Australia.
Opal and amber are not minerals.
It is called the opal.
Opal and amber are not minerals.
Opal
An opal is considered to be a semi-precious stone. It is a naturally occurring glass.
If the opal has fire, play of color, it is used for jewelry. Very little gem quality opal is imported by the USA. Most of it goes to Asia. The white opal you are used to seeing in the stores is not considered gem quality in the trade. Gem quality opal can cost thousands of dollars a carat. Opal can be man made. It is produced for research to see if it can be more efficient in transmitting light than optic cable.
Orthoclase
Virgin Valley black fire opal
Most likely Opal
opal
They have to dig for it There are several different mining sites in Australia where different types of opal is found.