Madagascar Green Dendritic Opal 8mm Round - 15-16 Inch BirdsEye Biotite is a name used

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

whose name is derived from the Greek word for Rose

with mirrored or coordinating patterns that bring strong color

They are all silicate minerals

Madagascar Green Dendritic Opal 8mm Round - 15-16 Inch BirdsEye Biotite is a name usedThis 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.