DYKES, MINERAL VEINS, &c. 
87 
Mineral Veins . — The principal products of the mountain limestone 
tract of Yorkshire are sulphuret of lead, carbonate of lead, sulphuret 
of copper, sulphuret of iron, carbonate of iron, and oxide of iron, 
sulphuret of zinc, carbonate of zinc, and white oxide of zinc ; of these 
all, excepting the iron ores, are invariably connected with spars veins, 
fissures, or rock dykes : and these are the most general repository for 
iron pyrites, which also occurs near the junctions of sedimentary rocks 
with the Whin sill. 
It is important to remark, that no instance is known, along the 
Penine region, of any one vein being continuous from the slates of 
Cumbria into the mountain limestone tract ; no case is, I believe, known 
of any vein being worked in old red sandstone ; no vein has been worked 
(in Yorkshire) above the upper or Brimham millstone grit : though 
lead ore has occurred in veins in coal seams above that rock, and strings, 
and nests of lead ore, and copper ore, have been met with in magnesian 
limestone at Nosterfiekl, Farnley, Newton Kyme, and Warmsworth. 
Calamine and white oxide of zinc occur in considerable quantities, 
chiefly or wholly in the lower scar limestones, as in Bolland, 
near Whitewell ; near Malham ; south of Wensleydale it is in the 
lower scar limestone, principally, that the lead mines of Greenhow, 
Nidderdale, Grassington, Kettlewell, Arncliffe, Hardfiask, and Ingle- 
borough, are or were worked ; but to the north of Wensleydale the 
Cam limestones become the most productive. In the mining districts 
of Greenhow, Grassington, and Kettlewell, veins yield ore both in the 
limestone and millstone grit series. Veins have been found more or 
less productive in the millstone grit series, south of Lothersdale, about 
Greenhow hill, Grassington, Buckden pike, near Leyburn, and in the line 
of the Auldgang vein in Swaledale and Arkendale. Mines are worked 
in the Whin sill, at several points, north of Maize beck. 
From these facts it follows, that the dependence of particular metallic 
products on particular series of rocks is principally a local phenomenon, 
without general application ; but on more minute analysis of the 
