﻿282 MR. A. M. FINLAYSON ON THE [May 1 9 10, 



it is open to question whether, in the realm of ore -deposits as in 

 that of petrography, a truly natural classification is yet attainable, 

 at least on an analytical basis. The following classification of 

 British ores is based mainly on the system evolved by W. H. Weed, * 

 the subdivision of the veins, however, being adapted from that of 

 the Freiberg school of mineralogists : — 



I. Igneous (magmatic segregations). 



(a) Dykes and veins : Grainsgill wolfram-pegmatites. Cam Chuinneag 



tin-bearing magnetite. 



(b) Disseminations : Molybdenite in granites. 

 II. Igneous emanations. 



Contact-metamorphic : Loch Fyne nickeliferous pyrrhotite. 

 III. Fumarolic deposits : Zeolitic copper-ores in the Carboniferous lavas of 



Renfrewshire and Dumbartonshire. 

 IV. Gas-aqueous deposits. (Veins.) 



A. Veins of oxide-ores. 



(1) Spathic iron-ore veins: I v (3) Manganese-ore veins: 



Cumberland. Merionethshire. 



(2) Red haematite veins. ; (4) Tin veins : Cornwall. 



B. Veins of sulphide-ores. 



(5) Copper veins. 

 Tourmaline-copper 



Cornwall. 

 Quartz-copper : 



Coniston. 

 Spathic copper : 



Exton. 



(6) Silver-lead and zinc 



veins. 

 Quartz-lead : 



Cardiganshire. 

 Spathic lead: 



Flintshire. 

 Barytic lead : 



Shropshire. 



(7) Rich (noble) silver-ore veins. 



Silver-quartz : ? 



Silver-calcspar : Hilderston, 



Alva. 

 Silver-copper : Cornwall. 

 Silver-cobalt: Hilderston. 



(8) Gold veins. 



Gold-copper and pyritic 

 quartz : Merionethshire. 



(9) Antimony-veins : Knipes, 



Dumfriesshire. 

 (10) Cobalt, nickel, and bismuth 

 veins : occur locally in 

 Cornwall,the Lake District, 

 Hilderston, Killarney, etc. 



V. Metamorphic deposits. 



Fahlbands of the Scottish Highlands. 



The value of such a classification lies in the fact that it crystallizes 

 views on genesis and on matters of detail ; but, taken alone, it gives 

 an incomplete survey of the ore-deposits, and it must therefore be 

 supplemented by a study of the metallogeny as a whole, in order to 

 bring the ore-deposits into their natural position in the geological 

 record. 



II. Epochs of Sub-Ckustal and Igneous Activity 

 in the British Akea. 



The complete history of the area, and its gradual evolution 

 through periods of depression and sedimentation on the one hand, 

 and periods of uplift and folding with igneous intrusions on the 



1 'The Classification of Ore-Deposits: a Proposal & a Discussion ' Eng. 

 & Min. Journ. New York, 1903. 



