32 TlMEHRI. 
in the eruptive rocks, and as the sedimentary rocks so 
called are built up from the ruins of these, the presence 
of precious metals in them is easily accounted for- 
Geologists tell us that the " mother vein", the source of 
all gold, is of an unknown geological age but is older 
than the formations in which gold is found — and that but 
for the upheaval of certain rocks which is continually but 
slowly going on, gold would never have been known. 
Gold is found either as free gold in the form of nuggets, 
which may be lumps of several pounds weight or as 
minute grains, or as veins, more or less perceptible, 
permeating other geological formations as quartz, clay, &c. 
Certain metals are always found together, gold and iron 
are always associated, just as lead always contains silver. 
HUMBOLDT stated that in Guiana gold is sometimes dis- 
seminated in an imperceptible degree in the granite rocks 
without any evidence of small veins, and in New South 
Wales granite, and in Siberia, clay and slate are permeated 
by small particles of gold. Dr. Percy the celebrated 
English Metallurgist, thinks that gold is precipitated from 
an aqueous solution, while Sir Roderick MuRCHlSON, 
who it will be remembered foretold the discovery of 
gold in Australia, believed that quartz is of volcanic origin 
and at one time was in a gelatinous condition in which 
it enclosed gold mechanically. Gold is found more or 
less abundantly in every part of the earth, and gold mines 
have been worked from the time of the Phoenicians. 
But it is not intended to enter into the geology of the 
precious metal nor the history of its mines, but rather to 
select those portions of the reports dealing practically 
with its colle6tion &c, which may be of use to the gold- 
seekers of British Guiana. 
