The hostrocks of the mineralized features are mapped as brown micaceous qartzite, fine-grained mica schist and minor limestone of the Mississippian to Lower Permian Milford Group (Bulletin 53, Figure 3). Minor amounts of disseminated galena and sphalerite are found in some limestone and quartz veins. Gouge and breccia from the main shear zone varies in thickness from 0.6 to 6 metres.

These claims are located about 1 kilometres southwest of Ainsworth and may be reached by about 6.4 kilometres of road that winds up the mountain side. They adjoin the Highlander and Albion claims on the west.

In 1892 the Black Diamond and Little Donald claims were owned by J.F. Stevens of St. Paul, Minnesota. A joint 4001 crosscut tunnel was driven on the dividing line between the Black Diamond and Little Phil claims. Two veins were reached. The first one was driven on for 61 metres, the second for 14 metres.

The Highlander Mining and Milling Co. took over the Black Diamond and Little Donald claims in 1899. The Highlander tunnel, driven from the Eagle claim at the foot of a high bluff, cut the two Black Diamond veins, the first at 760 metres, the second, at 795 metres. The dip of the veins at this horizon is about 260. The Highlander mine closed in 1911 and the property lay idle until 1949.

Yale Lead and Zinc Mines Ltd. obtained the property in 1949. Leasers shipped the old dump and did about 30 metres of drifting during 1949 and 1950. The company mined the Black Diamond in 1951 and early 1952 and the Little Phil for the balance of 1952.

Intermittent mining occurred from 1895 to 1964. A total of 985 tonnes were mined. From this, 701,872 grams of silver, 31 grams of gold, 335,273 kilograms of lead, 13,935 kilograms of zinc and 26 kilograms of cadmium were recovered.