This Boulder Opal is named 'The Galaxy' and is possibly the finest Boulder ever found. It weighs a staggering 2600 carats.
4.00 cts brilliant red fire boulder opal jo2119
Boulder Opal Stones 16 x 6 x 3mm 4 carats Auction #321733 Opal Auctions
Boulder opal is found in Australia where precious opal forms in veins and patches within brown ironstone boulders. When the opal is mixed through the ironstone it is called matrix opal. Hardness ranges between 5.5 and 6 on the Mohs scale.