98 



Tli". Geol'xjy of tlie Gold Flclih of British Guiana. 



The minei-alogical compositions of the somewhat altered diabase 

 containino; hornblende and chlorite are as follows ; — 



The rock from the Essecjuibn-Potaro district is an Auvertfnose and 

 that from the Mazaruni an Andose. 



