Figure 4. Stratigraphic units at Aljustrel. The coloured units represent the most recent subdivision -- the volcanic units were identified by Ore Systems Consulting using lithogeochemical data. The Fetais orebody lies on rhyolite A and is overlain by rhyolite C, while the Moinho orebody lies on rhyolite B. A quartz-feldspar porphyry which outcrops over much of the central part of the Aljustrel area is interpreted to be largely a subvolcanic mass, which locally fed small extrusive flows above the level of the ores.