With an Account of the recently discovered Buhrstone. 25^ 
among the miners of this district, who are said, in some instan- 
ces, to have carried their •prejudices against north and south veins 
so far, as to have abandoned promising veins in this direction, 
on meeting with a trifling shift, the removal of which afterwards 
enriched more enterprising adventurers. Indeed, one is tempted, 
from the accounts given by the miners, to imagine, that the 
richest veins in the chert of this place run east and west, while 
the most profitable veins in the limestone lie in a north and 
south direction. There is another considerable mine on the 
north-west summit of Halkin, called Gelly-Fowler-Fields^ which 
for some time yielded much green phosphate of lead ; but this 
ore has lately become scarcer, and the galena has become more 
abundant. The large mass of green phosphate above mentioned 
was found in this mine 4 but this ore occurs both massive and 
crystallized in other parts of this mountain, 
Halkin is much less steep on its western than its eastern side. 
On the former it gradually slopes into a wide cultivated valley, 
which extends to the third range of Flintshire hills. Its gene- 
ral direction is NNW. and SSE., extending between three and 
four miles in length, with a medial breadth of less than a mile. 
Its top is undulated, presenting a considerable extent of irregu- 
lar plain, sterile, and in many places rocky. The limestone has 
already been sufficiently described, but the slaty rock and chert 
require a more particular detail. The upper rock on some 
parts of the mountain cannot be easily distinguished from com- 
mon shale, crumbling down on exposure to the air, into small 
angular fragments, which, by farther decomposition < are resolved 
into clay. Below this lies a slaty rock, often veined and cloud- 
ed with various shades of grey ; its lower strata become hard- 
er, and it passes gradually into a true siliceous-slate. This 
rock, in the state intermediate between shale and siliceousrslate, 
occurs in large quantity in the hill just above Holywell, where 
it is much used lor building. It is usually prettily veined with 
parallel lines of dark and light grey colours ; it is tolerably 
hard, but may be easily scratched with a knife ; its specific 
gravity I found to be S.4885. Its stratification becomes less 
and less distinctly visible, as we trace it downward ; its hard- 
ness and density increases, its fracture inclines to splintery, and 
it finally passes into the chert^ which appears to me to be a 
