“…Labrenz et al [52] observed spharelite in natural biofilms of sulfate reducing bacteria, and Jandová et al [53] obtained covellite from the precipitation of copper from manganese deep ocean nodules with (NH 4 ) 2 S. However, different results can be obtained as a function of the system applied and/or temperature. Rybicka et al [54] obtained crystalline CuS and ZnS from the precipitation in clay columns at 80 • C, whereas the precipitates were amorphous at room temperature.…”