This volcanic opal is a wood fossil.
Only several areas in Indonesia produce this opal and when
mined it is jet black color.
The opal miners wrap this opal in aluminium foil and then
heat to cook the opal and add oil so the oil penetrates inside the specimen.
The Indonesian opal can resemble branch configuration as cabochon
The body tone is not classed as N4 and above, so it is not
deemed a black opal.
opal collectors enjoy adding this opal to their collection
due to its bright colors and good value