A slickenside (striated fault surface) with an accretionary coating of azurite, pale brown serpentine, and probable calcite. The matrix is typical of much azurite from Sterling Hill: altered, franklinite-willemite ore in which the calcite is partly replaced by azurite and local orange-tan serpentine. The remaining calcite in the matrix rock fluoresces red SW; that on the slickenside does not. Ex Anthony Den Uyl collection, now specimen FMM-7638 of the Franklin Mineral Museum.
Identifier: AZR3a Locality: Sterling mine, Ogdensburg Specimen size: 9.5 x 9 x 6.5 cm Photo credit: Earl R. Verbeek