the idea of cornering the worlds most significant coltan reserves was both inspired and financially very profitable , but was not without precedent - the grey sludge of goma had been a commercial - not to mention actual - battleground for more than two decades ; drisdales real genius came in concealing his aggressive moves towards gaining a mineral monopoly beneath the guise of spiritual attainment , which superficially not only served to legitimise his aims but also provided him with a massive free workforce : the pilgrims of mancala were only too ready to take a turn sifting through the open cast mines of goma if by doing so they were brought closer to a higher state of enlightenment .