Tanzanian Opal is generally a green or honey color. These stones can have a very unique rolling flash sometimes with play of color.
When refering to Tanzanian Opal it can mean that the opal comes from either of the Tanzanian Opal mines.
Tanzanian Opal is similar to Jade and is also known as Prase Opal. There is also some Dendritic Opal found which is moss like inclusions that have formed in the Opal.