"Crystal opal" is a term used for a transparent to translucent opal material that has a play of color within the stone.
Crystal opals are often faceted to produce gems that have internal play of color and fire exiting from the facets.
Photos shown here are a crystal opal cabochon with blue to violet play of colors. It is a calibrated 8 x 6 millimeter stone cut from material mined at Lightning Ridge, Australia. Also a faceted Ethiopian crystal opal with a water clear body color and internal play of color. It is four millimeters across.
Sunstone: a feldspar with aventurescence caused by light reflecting from platy inclusions.
Volcanic Explosivity: Rating volcanic eruptions based upon the volume of tephra ejected.
Salt Glaciers are masses of salt that flow downslope under their own weight.
What is a Maar? The second most common volcanic landscape feature on Earth.
Minerals are the building blocks of our society. We use items made with them every day.
Rocks Galleries of igneous, sedimentary and metamorphic rock photos.
The stone shown here is a crystal opal with blue to violet play of colors. It is a calibrated 8 x 6 millimeter stone cut from material mined at Lightning Ridge, Australia.
The stone shown here is an Ethiopian crystal opal with water-clear body colors and internal play of color. It is four millimeters across.
