The Placer Deposits. 199 



and is very irregularly distributed through them. Very large nuggets, 

 one of which weighed 333 ounces, have been found from time to time 

 in this district. 



The placers in the Barama River Districts usually have from two 

 to as much as eight feet of yellowish to bluish clay over the gravels. 

 In the flatter and lower parts of the district, as near lanna and Hoorie 

 Creeks, in place of the clay, white quartz sand and whitish sandy clays 

 and sericitic earths are found, their thickness being from three to four 

 feet. The gravels consist, as a rule, of coarse, sub-angular white and 

 bluish-white quartz pebbles, and along some of the creeks are accom- 

 panied by boulders of hornblende-schist. The gravels vary in depth 

 from one to four feet, whilst their yield of gold varies from two and 

 a half to four pennyweights per cubic yard, the metal being 

 usually coarse. 



The Groete Creek and Ginjuni River Placers. — The Groete Creek 

 Placers are situated on White, Black, and Salt Creeks. They have 

 from two to five or six feet of reddish-brown or of yellowish clay above 

 the gold-bearing gravels. The gravels are usually about two feet in 

 thickness, and consist of coarse and of fine, more or less ferruginous, 

 angular pieces of quartz, with fragments of hornblende-schist and 

 irregularly shaped pebbles of concretionary ironstone. In places the 

 upper parts of the gravels are cemented by concretionary ironstone. 

 The (juartz of the gravel occasionally shows visible gold. The gold is, 

 as a rule, very fine and is sparingly distributed through the gravels ; 

 but in places the pay-dirt has yielded from one to one and a half 

 pennyweights of gold to the cubic yard. 



The Cuyuni River Placers are situated on the Oko, Arawak- 

 Matope, Arimu, Mariwa, Quartz Stone, Waiamu, St. John's and 

 Kopang Creeks. 



The Oko Creek Placers are situated twenty miles or more from the 

 river side. In the placers near the creek the gold-bearing gravels are 

 from one to two feet in thickness, and are covered by from five to, in 

 some places, as much as ten feet of yellow and reddish clay. The 

 gravels are ferruginous, sub-angular and somewhat coarse, their gold is 

 generally fine-grained, and their yields in places have amounted to over 

 three pennyweights of the metal to the cubic yard. The gravels on the 

 tributaries of the Oko vary from two and a half to four feet in thickness, 

 the red, yellow or yellowish-red clay covering them being from two to 

 five feet in depth. The gravel consists of coarse and of fine, angular, 

 ferruginous quartz with some large rounded stones. The average yield 

 per cubic yard is about one and a half pennyweights of gold, which in 

 placers on the main creeks is usually fine-grained, whilst in those in 

 the ravines it occurs in coarse, rough pieces. These placer gravels have 

 been mainly derived from amphibolite and hornblende-schist. 



The Arawak-Matope Placers are characterised by the coarseness 

 of their gravels and of their gold. Pieces of sericite-schist are found 

 in them. Their over-burden of ochreous clay is about six feet in 

 thickness. 



