a. Eng. Partly decomposed pyrite containing copper. Fay
b. In uranium mining, the term may mean ore containing a high proportion
of pitchblende, uraninite, coffinite, or vanoxite.
c. Cumb. A variety of hematite in hard pieces, some kidney shaped,
reaching the size of one's hand, in a moderately soft, dark-red, brown, or
nearly black mass of smit clay and manganese oxide, the whole having a
most confused appearance.
Dictionary of Mining, Mineral, and Related Terms