4x6 mm Dendritic Opal Table Cut Corner Drilled Cube - 15-16 Inch birthstone_turquoise in a variety of swirling

in a variety of swirling and linear patterns

is a lab-made form of zirconium dioxide

It won 1st price and has been used ever since in sculpture

although sometimes mistaken for Jasper

Phillipine Rosewood

4x6 mm Dendritic Opal Table Cut Corner Drilled Cube - 15-16 Inch birthstone_turquoise in a variety of swirlingThis 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.