Photo category: Rocks and Minerals specimen collection
- Photo taken Locality: Greece, Macedonia, Rodopi mt
- Photo taken by: Trichas, A.
- Photo taken date: October 2011
Photo of a sample of the mineral Opal, bought from the region of Rhodope, Greece in 2000. It is an amorphous, like glass, form of silica, massive with irregular fracture. The surface shows various alternating colors (white, brown, yellow, blue) with fluorescence. It has hardness of 5.5 to 6.5.