Several Types of Matrix with Opal

the Lightning Ridge NSW Australia variety is a highly silicified porcelin type that also comes kinda grungy meaning porous and the cutters get rid of it as it often pulls an opal into cracking with its porousness causing a drying out. The matrix from Andamooka is porous also and carries opal ( a leseer grade) the porosity allows the treatment with sugar and acid to make carbon molecules fill the pores creating "black matrix opal". The Queensland variety is an ironstone (ferrugenous sandstone) that acts as a host rock with speckles, veins, and pools and sheets of opal intermingling with the ironstone hence the name Ironstone Matrix Opal.Going on the road to sell some opal will not blog for a week.