Siglenlas mine, Nr. Llanidloes, Central Wales Orefield. These specimens of brecciated material are typical from this site. Some of the exposed chalcopyrite not yet weathered, displays the usual pale brassy colour. The specimens are made up of quartz, host rock, and chalcopyrite. I estimate the chalcopyrite content to be between five and ten percent, which would have made the processing economically viable.