In one week in April, 1864, almost 550 ounces of gold were mined from Gibralter Hill, a yield of more than 58 ounces per ton of ore.[4] In 1893 the Gibraltar Gold Mining Company exhibited gold ore from the hill at the World's Columbian Exposition in Chicago yielding a net of 6 ounces of gold per ton.[5]
In 1894 the Gibraltar Hill Company took 656 tons of ore from the hill, which yielded 2090 ounces of gold.[6] In 1895 more than 1500 ounces of gold were mined from the hill by the Gibraltar Gold Mining Company; by this time the yield was still 5 ounces per ton of ore.[7]
The mine was bought by English interests, with capital of £300,000, in 1896, and greatly expanded. £500,000 worth of gold was won before the grades declined and the company ceased mining,[8] in 1901. The mine then continued to be worked, on a small scale, by tribute miners. The company resumed operations in December 1907,[9] but the mine was closed by 1916.