An unusual light green with brownish center Opal nodule from Turkey.
Opal is a hydrated amorphous form of silica, an unusual stone is the sense that it is classified as a mineraloid, unlike other crystalline forms of silica known as minerals. Opal is subcategorised in 4 groups that includes a variable complex of stones. These interesting yellowish-brown opals are Classified as Opal -AG (Amorphous-Gel) A type of Opal consisting of aggregated spheres of amorphous silica, hydrated with water in between these structures.
The photos were taken in bright sunlight to bring out their best colours.
Unusual Opal nodule - Turkey
Size: 26 mm x 25 mm, 10 grams