112 ORIGIN AND DEVELOPMENT OF ORE-DEPOSITS. 



variously re-arranged, and sometimes locally concen- 

 trated by metamorpliic action. 



e. — Ores disseminated through sedimentary beds, 

 in which they have been chemically deposited after the 

 consolidation of the beds. 

 3. Unstratified. f. — Stockworks. 



g. — Impregnations. 

 h. — Segregated veins. 

 i. — Pipe veins. 

 /. — Pockets. 



h. — Bedded veins or floors. 

 I. — Crash veins. 

 m. — Contact deposits. 

 n. — Pake veins or lodes. 

 Of course, it must not be forgotten that in nature there is 

 no such hard and fast separation into groups as our classification 

 would indicate — such grouping is merely adopted for convenience 

 of study. The practical miner, and the observant mining stud- 

 ent, will be constantly meeting with phenomena which in some 

 respects would be best referred to one class — in others to 



another. 



Of these various kinds of ore-deposits those classed as 

 superficial are, in the West of England, for the most part of the 

 («) class. As they are to be separately dealt with in Chap. lY, 

 they need not be further alluded to here. 



Stratified deposits in the West of England are rarely, if 

 ever, of the (c) class, the rocks being too ancient. Some examples 

 of those referred to, classes {d) and {e), will be given in the next 

 section of the present chapter. 



Pahlbands may be defined as slightly impregnated or 

 mineralized belts of stratified rocks, coincident in strike and 

 dip with the general country rock. They are often traversed by 

 fissure lodes which extend beyond the limits of the fahlbands. 

 While the lodes are in the unimpregnated country they are 

 barren and valueless, but where they traverse the fahlbands they 

 are notably metalliferous. These phenomena are particularly 

 noticeable in the Kongsberg silver district in South Norway 

 and in the Gympie gold district in Queensland. They are not 

 exactly paralleled by any of the mineral phenomena of the West 



