A brother and sister duo from Australia have fulfilled an epic quest began by their parents decades ago. The family have been in search of opal their whole lives. They recently hit the jackpot, stumbling on a “unicorn pocket” of opal in southern Queensland, west of Brisbane. Like rainbows frozen in time, opals are one of the rarest, most precious and sought after gemstones on earth. The siblings unearthed a gargantuan 150-kilogram (approx. 330-pound) haul of the precious gemstones in the outback at a sight called Yowah in March, fulfilling their family’s two-generation quest. Isaac and Sophia Andreou are expert opal hunters, who learned the trade of opals—mining, cutting, polishing, appraising, and selling them—from masters in the field. Their parents began mining and selling opals in the 1960s, but never uncovered anything like this recent find. Australia is where some 90 percent of the world’s opals are found. Originally from Sydney, Isaac now …