San Bernardino County:
Frank Riggs was born in Michigan in 1845. In 1875 he married Sarah and soon after made the first discovery in the Silurian Hills at the Alta Mine. They had four children. Riggs became somewhat a celebrity with his incredibly rich silver mine, and unorthodox method of shipping ore. A 1908 article by the American Mining Review reported, "When Riggs had found the first ore, instead of seeking to interest capital in his find, as most prospectors would have done, he decided that the mine should be owned by himself alone. The first shipment that Riggs sent out went to San Francisco and the returns enabled him to build a home at the mine, where he has lived since while working the property. Since then shipments have left the Riggs mine consigned to Selby's by express. These enabled Riggs to live well and improve his property." Prior to construction of the California Eastern Railroad in 1893 he brought the ore to Daggett for shipment, but with completion of the California Eastern he brought it to the railhead at Manvel. One 1904 shipment, which wasn't out of the ordinary, was noted by the Los Angeles Mining Review, "Mr. Frank Riggs shipped another small lot of specimen ore to the Selby Smelting and Lead Company, San Francisco, last week - about twelve sacks. The last lots ran something like $10,000 to the ton, and as this lot was again shipped by express it may be supposed that it was of about the same value. It is almost pure silver." To add to the mystique of the mine was his secrecy. The Redlands Citrograph in 1903 reported, "No living man today knows just what Riggs has. Parties who have been at his place have seen a shaft, and down this shaft there is a drift fitted by a heavy massive door. What lies behind this door is a mystery."
Sarah was a full partner in this enterprise. Her role and reward for this spartan life on the Mojave was well described as follows, "Together they do all the work. Their shipments are prepared with great care. After the ore has been mined it is carefully broken and sorted... Riggs and his wife lead a dual existence. About half the year they work their property, Mrs. Riggs working side by side with her husband. Then, after they have made a few shipments they travel. To paraphrase, [the] object is no money to them. They can enjoy their outings secure in the knowledge that the is more where the present comes from." Frank continued to mine here until the death of his wife on April 11, 1914, shortly after her seventieth birthday in February. She was buried in Michigan. Frank, six months younger than his wife was no youngster himself. In June he leased the mine to the Riggs Mining Company, that immediately began shipping ore via the Tonopah and Tidewater Railroad. It has been stated that before 1914 the mine had produced $100,000 in silver and by 1920 another $100,000 had been produced. The mine was active between 1939 and 1943 when a 1,700 foot crosscut was driven to intersect the vein, and a 1,500 foot tram was constructed.