Coarse-grained rutile from regolith in Ebensuk west of Tinto, Cameroon

摘要

Coarse rutile with some grains exceeding 32 mm was recovered from regolith excavated from three pits (ABC) at Ebensuk. The rutile concentration ranges from 2.53 kg/m3 of regolith material in Pit C to 2.83 kg/m3 in Pit B with an average of 2.66 kg/m3. The rutile is black, longitudinally striated, with a metallic to adamantine luster and hard. Results of grain size (Z) analysis show that the rutile crystals range in size from 4mm to Z32 mm. The grains are predominantly concentrated in the 16Z<32 mm size grade with a wt% of 48.3 followed by Z32 mm and 8Z 96 wt%, and subordinate Fe2O (2.2-3.1 wt%), and minor amounts of Al2O3, SO3, K2O P2O5 and Mn2O3 for all the samples analyzed, and meets international specifications for economic rutile ores. The rutile must have been derived through weathering of the underlying gneisses and their coarse nature is probably indicative of a possible source from granite pegmatite veins occurring in the gneisses outcropping in the study area.