sentences:  The leading historical gold-producing district is the Boise Basin in Boise County, which was discovered in 1862 and produced 2.9 million troy ounces (90.2 tonnes), mostly from placers.The French Creek-Florence district in Idaho County began in the 1860s, and has produced about 1 million troy ounces (31 tonnes) from placers.The Silver City district in Owyhee County began producing in 1863, and made over 1 million troy ounces (31 tonnes), mostly from lode deposits.