. The geology of the goldfields of British Guiana. f coarse,angular fragments of quartz, intermingled with pebbles of more or lessdecomposed felsite, and, in places, with many nodules of concretionaryironstone—vary in thickness from one to three feet. The gold foundis coarse, and is very unevenly distributed. The Kopang Placers are situated towar*^ the head of the creeknear the Barama distiict. As a rule the overburden of brown clay isnot deep, and the gravel consists of coarse quartz pebbles which do notshow visible gold. The gold obtained is usually fine-grained, and thegravel has yielded at
. The geology of the goldfields of British Guiana. f coarse,angular fragments of quartz, intermingled with pebbles of more or lessdecomposed felsite, and, in places, with many nodules of concretionaryironstone—vary in thickness from one to three feet. The gold foundis coarse, and is very unevenly distributed. The Kopang Placers are situated towar*^ the head of the creeknear the Barama distiict. As a rule the overburden of brown clay isnot deep, and the gravel consists of coarse quartz pebbles which do notshow visible gold. The gold obtained is usually fine-grained, and thegravel has yielded at the rate of two to three pennyweights of themetal per cubic yard of pay-dirt. The Mazaruni and Puruni Placers.—The Puruni Placers are themore important of these. They have an advantage over most of thosein other districts of the colony in being, as a rule, relativelj^ near thebanks of the river. Some are situated almost directly on them ; whilstthe average distance of the placers is not more than four miles from [ To fare page 200, IlATE 29,. i^^sysu PLACER WORKING. SLUICE AND CIIIXKSE PUMP AT ?\V01tK. Photo by C. TV. Anderson. rh>^ Plactr Deposit. 201 the river. The overburden is a reddish-yellow to a deep red clay,varying in depth from eight to ten feet. The gravels consist near thewater-side of water-worn quartz pebbles, and at a distance from it ofaiigular to sub-angular fragments of quartz, with nodules of con-cretionary ironstone. In places pieces of quartz, carrying more or lessfree gold, are found in the gravel. The gravels yield from two and ahalf to three and a half pennyweights of gold per cubic yard. Anugget weighing ninety ounces was found in this district. The only jjlacers of importance which have been worked on theMazaruni Paver are the very productive ones on the Isenaro Creek,st)me miles below the Peiamah Falls. The valley-placers consist ofmore or less angular fragments of quartz, fragments of partiallydecomposed granite and greenstone, with abundance
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