Amphibole and quartz are the major gangue constituents. FER-3 is from the west pit in the north limb of the Tetapaga incline containing metavolcanic and pyroclastic rocks. Quartz is the most abundant mineral present.
Hematite occurs as dusty inclusions in the quartz, but as micro-laminae in jasper layers.
0.2 0.72 CO2 1.39 0.07 1.2 4.86 P2O5 2.39 0.27 0.07 0.13 F 0.06 0.04 0.01 0.02 S 0.26 0.17 0.03 0.11 Values in italics are provisionally recommended.