Figure 18. Reconstructed setting of the Fetais massive sulfide deposit, Aljustrel, showing the positions of the chemically defined volcanic units, the cherty exhalites overlying rhyolite C and the orebody, the three main facies of massive sulfides, the underlying stockwork (which lies in rhyolite A), and the mass change effects in the stockwork. The cherty exhalites range from pure cherts to Fe-rich (hematite, magnetite, pyrite) or Mn-rich or barite-rich varieties.