RAKE VEINS, PIPE VEINS, AND FLAT VEINS. 403 



concurrence of lead glance, and blende, or calamine, and copper pyrites ; 

 of cobalt, copper, nickel, and native bismuth ; of tin, wolfram, tung- 

 sten, molybdena, and arsenical pyrites ; of topaz, fluor spar, apatite, 

 schorl, mica, chlorite, and lithomarge ; of brown ironstone, black iron- 

 stone, manganese, and heavy spar. He says where tin occurs, ores of 

 silver, lead, and cobalt, and vein-stuffs of heavy spar, calcareous spar, 

 and gypsum are rarely found. Cinnabar and other ores of mercury 

 scarcely ever occur with the ores of other metals, except iron ochre 

 and iron pyrites. 



Rolled and Fragmental Masses. That fragmental masses of the 

 neighbouring rocks should be found in mineral veins, cannot be thought 

 surprising. It is a common occurrence in mining districts, both in 

 Primary and Secondary rocks. Thus gneiss at Joachimsthal, clay 

 slate in Cornwall, limestone in Cumberland, are included in the veins. 

 Werner mentions a vein in Danielstollen at Joachimsthal, fourteen 

 inches wide, which at one hundred and eighty fathoms depth was 

 almost entirely composed of rolled pieces of gneiss, some of them 

 nearly spherical. In the Stoll Kefier, near Kiegelsdorf, a vein of 

 cobalt was cut through by another vein of sand and rolled pieces. 

 These examples seem trustworthy, but we must always be careful to 

 discriminate between rolled pebbles and concretionary masses. 



General Forms of Veins. Mineral veins are usually distinguished 

 by miners into several kinds, according to their form and direction, 

 because these circumstances are the most influential in the arrangement 

 of their works. Ralte veins, the most common and characteristic, may 

 be considered to fill long, narrow joint-fissures or faults, which pass 

 in a vertical or highly inclined direction downwards from the surface 

 through a great thickness of the subjacent rocks, whatever these may 

 be, and preserve nearly the same angle of inclination and the same 

 linear direction through their whole course. Pipe veins are also highly 

 inclined, and pass downward in the same manner, but they rather 

 resemble irregular channels than fissures, and are subject to great 

 swellings and contractions of their diameter. They sometimes pass 

 downward along the stratification ; in other cases penetrate through 

 the substance of the strata. The copper mines in the neighbourhood 

 of Ecton, in Staffordshire, are in pipe veins. The irregular cavity of 

 copper ore, which forms the celebrated Parys mine in Anglesea, and 

 the iron mines of Dannemora in Sweden, may be pipe veins, or 

 stock works. Flat veins or streaks, as far as we are acquainted with 

 them, seem hardly to deserve a special name, being only portions of 

 rake veins which have been changed in their inclination, and made 

 to pass for limited distances parallel to the beds. In the limestone 

 districts of the North of England, this happens principally in connec- 

 tion with certain limestone beds. The term Gash veins denotes such 

 as range for considerable lengths, like rake veins, but are wide at top, 

 and grow narrower downwards, till they entirely vanish. This is rare, 

 though many veins grow narrower downwards. 



Strings. Perfect parallelism of the sides or walls of a rake vein, 

 which is the most regular of all, is a rare phenomenon. Most com- 



