114 TlMEHRI. 
clay covered with a layer of decomposed vegetable matter 
and is also of varying thickness. The average may be 
taken as 5 feet. This auriferous bed is composed of 
quartz fragments, and other mineral resting on the clay, 
with fine band above — thus the gold owing to its high 
specific gravity is found in greater quantities in the 
deeper and coarser portions of the bed. 
In British Guiana it will be noticed on consulting 
the geological map of the Colony that the auriferous 
areas at present being worked are without exception along 
the line of the vast dykes of greenstone which intersect 
the Country from North-west to South-east. In the 
Potaro and Canawarook districts we find the green- 
stone in contact with quartz-porphyry and felstone, while 
at Omai the bed rock appears to be granite. The same 
remark applies to the Cuyuni and Massaruni, except that 
on the higher Cuyuni there is a vast area of schist and 
gneiss. 
The coarseness of the gold varies, but the largest 
nugget hitherto obtained was that found by Mr. FRASER 
LUCKIE in the Canawarook in May 1891, and which 
weighed forty-two pounds and a half. This is small in 
comparison with the ,f Welcome Stranger" nugget found 
at Donolley in Victoria which gave 2,268 ounces of 
gold. 
There has been much speculation as to whether there 
are any deep leads in this colony, but at present all the 
workings have been shallow. 
With regard to quartz-mining, great hopes are held 
that the end of the present year will see quartz crushing 
machinery at work on the upper Demerara river and per- 
haps on the Barima. Sample crushings which have been 
