In his account of irregular rake veins,
Mr. W. obferves, that the bed concomitants
of ore are the fpars, and vein ftones
or riders. His account of the fpars- is
pretty accurate, confidered as calcareous, as.
cawk or barytes, and quartz. In p. 288,
he gives a curious account of lochs or the
cavities in mines, and the beautiful fpe-
cimens of copper found at Colvend in Galloway.
He then enumerates the foft fub-
ftan'ces found in veins, particularly that
refembling fnuff, or the guhr of the Germans.
Other circumftances attending veins
are enumerated with care, and in general
this fecond part of his work is by far the
moft precife and inftrudfcive ; but cannot
pretend to any praife of arrangement.
In p. 314, he defcribes a beautiful ore
of the Lead Hills, being a yellow efflo-
refcence near an inch deep, of a fibrous
or columnar texture upon the blue galena.
After
After a full account of the rake or perpendicular
vein, becaufe it is the moft common,
he proceeds p. 321 to eonfider the pipe
vein. The mining field of Ilay, he fays,
confifts of ftring veins, and fubjoins fome
account of them. The pipe vein he defcribes
p. 331, as varying from the horizontal
to the declination of 45 or more.
He obferves that the lochs are open fpaces,
and more frequent in the pipe veins.
The flat or dilated vein or ftreek, lie
between ftrata like fleams of coal, and commonly
occur in argillaceous ftrata.
The accumulated vein, commonly re-
fembles a vcoal direflt or inverted, and is
ufually the richeft of any.
Mr. W. then proceeds to explain the
various flips, troubles, and other incidents
which occur in metallic veins; and obferves
that ore is fometimes found interwoven
as if it were with the rock, yet
worth