Roebling Black Opal from Virgin Valley, Nevada

The famous fist-sized "Roebling" Black Opal from the Rainbow Ridge Mine, Virgin Valley, Humboldt County, Nevada, USA. Dug in either November 1917 or 1919 in the underground tunneled portion of the mine, found by miner Lew Thompson while working in the mine for Flora Lockheed and the Rainbow Ridge Mining Company. This Opal was held in 1920 to be worth US$250,000.- and called the most valuable or expensive opal at that time, which was subsequently acquired by mineral collector Washington Roebling, and donated in 1926 to the US National Museum (Smithsonian) by John Roebling, where it still resides in the permanent collection today, Catalog #R-22. It weighs 2,585 carats (approximately 517 grams or 18.24 ounces). It is on display in the mineral hall in the opal display.