268 A. R. Andrew—The Dolgelley Grold-belt. 
or Menevian black slates. Some of the auriferous veins may extend 
into the. Gamlan Beds, but they appear to lose their auriferous 
character. Again, no vein is known to be auriferous above the lower 
part of the Ffestiniog Flags. The only formations in this Dolgelley 
Gold-belt which are intersected by auriferous quartz-veins are the 
Menevian (Clogau), the Maentwrog (Vigra and Pen Rhos), and a small 
part of the Ffestiniog—a total thickness of about 3600 feet. 
Throughout the gold-belt of Dolgelley the igneous intrusions 
greenstones) are for the most part not of large extent; it is only the 
larger ones that are noted on the geological maps which accompany this 
paper; they are, however, very numerous, and the auriferous veins 
are found close to them, often, if not always, forming part of the wall 
or walls. The Dolgelley lodes appear to have no gossan; underground 
their characters appear to be similar to those they possess at the 
outcrop. 
Reviewing the facts concerning the occurrence of the auriferous 
veins of Merionethshire, we may say: 
(1) That the usual strike of the auriferous lodes is north-east and 
south-west, in some cases diverging to east and west, in others to north 
and south; the bulk, however, strike north-east and south-west. 
(2) That there is no difference in mineral contents between the 
veins that range north-east and south-west and those that range east 
and west, or north and south. 
(3) That auriferous veins are not found below the Clogau or 
Menevian Beds. 
(4) That they occur only in black carbonaceous slates or shales, 
rich in pyrites. 
(5) That they are associated always more or less intimately with 
igneous intrusions. 
(6) That the lode material consists usually of quartz, often with 
calcite and impregnated country rock. In one case (Glasdir) the 
whole material of the lode consists of ‘these impregnated shales 
and flags. 
(7) That the most usual minerals associated with the gold are 
blende (sphalerite), chalcopyrite, galena, and pyrites. 
(8) That the gold is usually coarse, granular or aggregated, and 
seldom shows crystalline faces; rarely it occurs finely disseminated 
through the quartz. 
(9) That the distribution of the gold in the lodes is very capricious, 
and is not known to follow any regular law, though it appears most 
possible that it may be regulated by the fractures or cross-courses 
which intersect the lodes. Whatever the cause of the rich pockets, 
on them depends the future success of the mines, and until the law 
regulating their distribution is discovered, the mining of these lodes 
will always entail even more uncertainty than that which is usually 
associated with any gold-mining. It seems that it might be advisable, 
in the case of those mines now at work, to investigate as far as 
possible the influence that these cross-courses have on the distribution 
of the gold in the lodes. 
(10) That in the upper portions of these lodes there is no conspicuous 
belt of ordinary weathering, though as work on these lodes has not 
