Madagascar Dendiritc Green Opal 10mm Round A Grade - 15-16 Inch 6-8x12-25mm and much of the black

and much of the black Onyx on the market has been artificially colored

or some degree of pink in between

Biotite is a name used for a large group of black mica minerals that are commonly found in igneous and metamorphic rocks

Handy Zip-Pouch

Madagascar Dendiritc Green Opal 10mm Round A Grade - 15-16 Inch 6-8x12-25mm and much of the blackThis variety of opal is named "dendritic" for the small inclusions within it that resemble moss or ferns. These inclusions consist of iron, manganese and other metallic oxides captured during the forming of the rock. Opals are hydrated amorphous forms of silica, created when silica hardens within the fissures of other stones.