Section IV., 1885. [ 23 ] Trans. Eoy. Sog. Canada. 



II. — On the WaUhridge Heumiite Mine, as ill mt rating the Stoch-foi-ined Mode of 

 OccKrrence of certain Ore-Deposits. By E. J. Chapman, Ph. D., LL.D. 



(Read May 28, 1885.) 



Metalliferous deposits, viewed broadly, may be regarded as falling i;uder the follow- 

 ing snb-divisious : Veins, stocks, net-works, gash-lodes, impregnations, beds, alluvions. 

 Briefly defined, without regard to accidental or local conditions, these are characterized as 

 follows : — 



Veins are ancient fissures filled up, forming, as a rule, comparatively narrow sheets of 

 mineral matter, which commonly pass through various kinds of rock without regard to 

 the strike or dip of these, and which, normally, extend downward to great depths. 



Stocks are limited masses of ore, although often of large dimensions, lenticular or 

 irregular in form, and inclined or horizontal in position. In some cases, they conform 

 more or less to the structural characters of the rocks in which they occur; in other and 

 perhaiîs the majority of cases, they shew no relations of this kind, but occupy a totally 

 independent position as regards the enclosing rock. 



Net-works, sometimes called Stock-works, are assemblages of narrow, reticulating 

 veins, branching irregularly through the enclosing rock, and commonly tapering off and 

 dying out in thin strings. 



GrASH-LODES are simply narrow, often more or less linear, stocks, usually of short 

 length, but commonly occurring in closely adjacent parallel bands, thus resembling a 

 series of short, broken veins. As a rule, they consist wholly of metallic mattei-, without 

 any accompanying veinstone or trace of vein structure. 



Impregnations consist of metallic matters diffused through zones or areas of rock in 

 small, often imperceptible, particles, or in patches or stains. Impregnations or diffusions 

 of this kind are occasionally of independent occurrence ; but more commonly they occur in 

 intimate connection with veins, stocks, or other ore-deposits, being evidently emanations 

 from these, or otherwise due to similar causes. 



Beds are deposits of mineral matter lying parallel, or practically parallel, with the 

 stratification or foliation of the rocks in which they occur, and never extending iipward 

 in strings or other prolongations into the overlying rock, as they are necessarily of earlier 

 deposition than the latter. 



Alluvions cannot strictly be separated from beds proper, as they are simply beds or 

 bedded deposits of more or less superficial occurrence, but for practical purposes they are 

 couA-eniently classed apart. They consist of accumulations, from springs, streams and 

 rivers, of detrital or precipitated matters iu which metallic substances or other economic 

 products are present. 



As regards Canadian iron ores, the existence of stock-formed deposits hardly seems to 

 have been recognized, if recognized at all, in the earlier explorations of the country. Many 

 of our iron-ore deposits, perhaps the majority, are nevertheless in that condition. In the 



