any regularity, or inclination of the ftratum,
but fill up fiflures; having found rock for
roofs and foies, the vein running more or
lefs horizontally. They are fometimes of
great magnitude, twenty or thirty yards
wide, and fometimes fo (lender as not to
exceed two inches.
Pipe veins are always attended with a
confiderable portion of clay, which, when
the vein becomes imperceptible, will be a
fure guide to follow; and from the appearance
of a few inches of clay only, purfuing'
it a few feet, the vein has been found of
confiderable extent. Such is the irregularity
of pipe veins. The gangart of the pipe is
different from that of the rakes, and they
moft commonly have the toadfione in the
vicinity, either above or below.
The principal pipe veins are Yate (loop,
near Winder; Hubberdale, near Moneyafh
;
afh; Watergrove, Millermine, and Lane-
head at Caftleton.
In the neighbourhood of Wirkfworth,
Matlock, Bonfal, Caftleton, &c. are many
veins containing blende or black jack, ful-
phuret of zinc ; calamine, lapis calaminaris,
or native oxyd of zinc; barytes, calcareous
fpar, &c.
At Braflington Moor, north weft of
Wirkfworth, are carbonates of lead, irons,
fteatite, calamine, and blende. The white
lead ore is commonly in lums. Thefe minerals
are chiefly found under loofe fandy adventitious
matter, which might deferve the
attention of the geologift. Black wad, an
ore of manganefe, is found near Youlgrave.
The fluor fpar mines at Caftleton are in-
terelling to curiofity, as they (hew fuch a
variety of lums, or broken ftrata, filled up
with adventitious matter, as are perhaps no
p 3 where