ivith an Account of the recently discovered Bttlir stone. 249 
Holywell, graduates, as it approaches the surface, into perfect 
shale. From the dip of this limestone formation to the east, it 
would appear to pass below the cosX’-measures of the lower 
range. Both the siliceous slate, and the limestone, abound in 
rich veins of lead-ore and calamine. The two substances are 
often found together The calamine is most abundant a little 
to the north of Holywell, on the roads of St Asaph and White- 
ford. This mineral was here so little known about a century 
ago, that the finest ores were employed as a material for repair- 
ing the highways ; but when its value was discovered, the roads 
were broken up, and limestone, or siliceous rock, substituted for 
the more valuable material. 
Some years ago I remarked an abundance of fine reniform 
or botryoidal calamine in the mines round Holywell, and found 
crystals of the same substance in many specimens. On a late 
visit I was unsuccessful in procuring either, the ore principally 
consisting of a much corroded calamine, in the state of oxide, of 
a dull yellowish-grey colour, sometimes varied with pale yellow, 
green, orange, and bluish tints, of great hardness, and con- 
siderable specific gravity. This ore usually accompanies galena. 
The lead-ore of this district is chiefly galena, but considerable 
quantities of green phosphate are occasionally found. I have 
specimens in prismatic crystals, but it is usually amorphous. 
I am in possession of a mass of green phosphate of lead, nearly 
pure, which weighs upwards of twenty pounds avoirdupois, 
I have also lately received specimens of rich indurated white- 
lead-ore from Bruen-mine near Holywell. Mixed with the lead 
and calamine, there is found much common brown blende, or 
sulphuret of zinc. The mineral veins in this district have a di- 
rection north and south, and also east and west. The latter, 
at least in the superficial veins, are considered as the most pro- 
ductive, but some of the richest veins on Halkin run north and 
south. The calamine is converted into brass ingots, plates, and 
wire, by mills, on Holywell stream. The lead is smelted in 
numerous furnaces, erected near the shores of the Dee, and the 
quality of the metal obtained is reckoned excellent. The quan- 
tity of silver in the Flintshire galena will not in general repay 
the cost of parting ; but the rich argentiferous galena of Car- 
diganshire is assayed for silver at the extensive works of Mr 
