Prof. Morris — Lead-mines of the North of England. 321 



frequently many names, according to the lease length, which is about 

 1200 yards. Cross veins commonly alter right veins, but not always 

 (as at Scaleburn cross vein), and right veins are often split, and 

 sometimes lost in cross veins. The " hade " is the inclination ; the 

 upper side is the "hanger," and the under side the "ledger cheek." 

 In Weardale the hade is south, in Allendale and Alston to the north 

 but it varies with the nature of the strata. The throw of veins is a 

 more or less vertical disruption of strata, but this is variable. There 

 is, however, a connection as well known to practical men between 

 the hade and throw of veins — if the throw is up to the south, the 

 hade is to the north and contrariwise. Veins are of different kinds, as 

 rake, pipe, strings, gash, flat veins. The rake vein is the most common, 

 and occupies a fissure extending downwards a considerable distance, 

 and may have opposite, similar, or dissimilar cheeks, and thus the 

 vein is more or less productive, and is irregular in size. The sub- 

 joined shows the character of the lode according to the nature of 

 the cheeks, although this is subject to modification : — 



Argillaceous Vein unproductive Argillaceous. 



Gritstone Vein irregular Grit or limestone. 



Argillaceous Vein poor Grit or limestone. 



Limestone Vein favourable Limestone. 



A gash vein is a fissure which contracts downwards. The " hade" 

 or inclination is mostly in the softer beds, and when two veins meet 

 they are generally enriched. Eegular veins have a slight throw, 

 and the size of veins depends on the nature of the rock, being generally 

 wider in limestone. A rider is the stony mass found in the vein, and 

 divides it. A pipe is an irregular cavern, extending downwards, and 

 is more or less tubular. A flat vein is a dilated vein in a space be- 

 tween two strata of stone, and resembles a coal seam, and inclines 

 TPith the strata. With regard to the difference of produce in the 

 various strata, the great limestone, at least in the Alston district, 

 seems to be the most productive, although in other localities other 

 strata are also productive. Mr. Forster mentions that the mines differ 

 on each side of the Burtreeford dyke, being softer on the east side, 

 and harder on the west, where they contain more blende and rider. The 

 chief minerals yielding lead are galena or sulphide, cerusite or carbo- 

 nate, and oxide of lead. The associated minerals are blende, calamine, 

 fluor, barytes, quartz, calc- and pearl-spar. It is said the cubical 

 galena yields a purer lead than the wavy galena, which contains 

 antimony. In the Cumberland district the phosphates and arseniates, 

 with cerusite, linarite, and caledonite, or the coloured ores, are the 

 chief lead ores, as at Eoughtengill and Drygill. 



Composition and character of the principal minerals from the dis- 

 tricts above mentioned : — Hardness. Sp. Grav. 



Galena Sulphide of lead Cubical 2o to 2-7 7-5 



Cerusite Carbonate of lead Rhombic 3 to 3-5 6*4 



Minium Oxide of lead Pulverulent 2 to 3 4-6 



Blende Sulphide of zinc Cubical 3-5to4 3-9to4 



Calamine Carbonate of zinc Ehombohedral .. 4 4 to4-4 



Fluor-spar Fluoride of calcium Cubical 4 3-1 



Heavy spar Sulphate of baryta Khombic 2-5to3o4'o 



VOL. VI.— NO. LXI. 21 



