This stone comes from the Quilpie mines in Queensland, Australia. It is basically a lump of local ironstone, on which a vein of blue opal has formed. The colour of the opal is a strong blue, and the main vein is ca. 3cm long and 1cm wide. There are other parts on his stone, which also contain blue opal. The entire chunk is 8.5cm long, 4.7cm wide and 2.5cm thick. It weighs roughly 200 grams on kitchen scales. I cannot cut a gemstone out of it, but it is a fine specimen for collectors.