This semi black opal comes from the Mintabie region of South Australia known for producing some of the hardest and most durable opal in the world.  The opal from this region is usually found in flat sheets referred to as plates and can vary in body tone and appearance all the way from clear crystal, to very dark, or black.  Not as much mining goes on in Mintabie these days as the living conditions are amongst the harshest on the planet, most of the best producing spots have been mined out and operating costs increase making stones from this area increasingly rarer.  The darker body tone opal from this field is often referred to as Mintabie black opal even though they often don’t fall into the N1 to N4 category on an approved body tone grading chart the term is still used and generally accepted.  This opal as well as some of my others stones fall into this category and generally command a higher price than the other milky colored and crystal opals from this area but remain a good cost p