Gems are generally cut with adhering andesite rock. This type opal is more stable than many others and the matrix makes for some very interesting picture cabs.
The Tablon mine is best known for its production of black matrix opal. This type opal is not dyed or sugar/acid treated to make it black. Sometimes it is sealed with a hot resin bath after the the cabs are finished then scrubbed and cleaned. This helps to seal the stone and prevent the cab from absorbing other substances such as skin oil, hand lotion and others.
The Tablon mine outside of the town of Erandique.Honduras and is the largest mine in the country as well as the oldest known opal mine in the world.
The color bands are within the vesicular black basalt and the opal is congealed within the rock itself. It cuts very stable stones as far as crazing or cracking. You will usually find very small pits in stones cut from this type opal because of it's slightly porous structure. As you can see in the cab pictured it makes some very nice stones