The laws which regulate the deposition of lead ore in veins; illustrated by an examination of geological structure of the mining districts of Alston Moor . es have been veins in the last-named districts difier also from those inAlston Moor in not containing much sulpliide of zinc. In the sandstones below the Great Limestone, the east andwest veins generally contain more quartzose minerals than inthe Slate Sills, Firestone, &c., or even in any of the veins in theGreat Limestone. In the Nenthead district, so far as the veinshave been proved in such strata, the sulphide of zinc dis-app
The laws which regulate the deposition of lead ore in veins; illustrated by an examination of geological structure of the mining districts of Alston Moor . es have been veins in the last-named districts difier also from those inAlston Moor in not containing much sulpliide of zinc. In the sandstones below the Great Limestone, the east andwest veins generally contain more quartzose minerals than inthe Slate Sills, Firestone, &c., or even in any of the veins in theGreat Limestone. In the Nenthead district, so far as the veinshave been proved in such strata, the sulphide of zinc dis-appears, at least it rarely occurs in masses as the principalmineral in the veins, though crystals of it, deposited upon thecarbonates of lime and iron, when such occur, are not unfre-quent. Quartz, however, is not the predominating mineral inall the strata below the Great Limestone, since both the eastand west, and north and south veins, occasionally contain somuch carbonate of Hme, in the limestone strata, as to be almost ??i/<fnc/uy /lie posclUii vfi-i irr/t l^:a</ ore dcpcnt in ( CROSS VEIN. Fu/.l. (jiiiod Liiru^ittrnt- OP VEIN MINERALS. 145 filled with it. For instance, in Carrs vein in Lovelady Shieldmine, and also Black AshgiU cross vein in the Four-fathomsLimestone, immediately below a very rich deposit of lead ore inthe G-reat Limestone. In this latter instance, the rhombohedralcleavage, so characteristic of calc-spar, is very distinct. Anumber of the veins proved in the Scar Limestone from Nent-force level, appears to be filled with carbonate of lime. Li thisstratimi GuddamgiU vein contains not less than three feet wideof this substance. HudgiU Bum cross vein (a continuationnorthward of Black AshgiU cross vein), contains an equal widthof it in the same stratum. Both east and west and north and south veins in the ScarLimestone, at its outcropping near the banks of the Tyne riverin GarrigiU, seem to be filled in a great measure w
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectgeology, bookyear1861
