As first identified by Gehrels and others (1983), the six massive sulfide occurrences represented by this site are virtually identical in hostrock, mineralogy, and genesis. Gehrels and others described the hostrocks as two volcanic units of the Silurian or Ordovician Descon Formation: one basalt or andesite; the other dacite or rhyolite. They distinguished the hostrocks from Cambrian or older Wales Group rocks to the north by the absence of a penetrative metamorphic fabric. S.M. Karl (oral communication, 2003), however, believes that the rocks are more metamorphosed than the Descon Formation and that they are a distinct Silurian or Ordovician metamorphic unit on southern Prince of Wales Island.

Most of the deposits are associated with layers several meters thick of fragmental, intermediate to silicic volcanic rocks. The sulfide minerals generally form thin layers less than 5 centimeters (cm) thick in the volcanic rocks, or form rinds around 5- to 20-cm-long volcanic fragments that may be flattened pillows. Sulfide minerals also occur in layers less than 5 cm thick in siliceous black slate and silicic volcanic rocks. The dominant sulfide is pyrite; the presence of arsenopyrite, galena, and sphalerite is indicated by spectrographic analysis of samples. Selected samples contain up to 30 parts per million (ppm) silver, more than 5,000 ppm barium, 30 ppm copper, 1,500 ppm lead, and 3,000 ppm zinc. The occurrences are probably syngenetic, submarine, and exhalative in origin. Later low-grade metamorphism resulted in local remobilization of the the metals.