■672 Dlt. J. A. THOMSON ON THE [Dec. 1913, 



and more particularly as to the importance of the porphyries in 

 determining the districts of albitization, -were elaborated by me 

 independently of Dr. Maelaren, and he cannot be considered as 

 committed to them. 



Much kind assistance in providing laboratory and library facilities 

 in Kalgoorlie was given by the Chamber of Mines of Western 

 Australia, the Lecturers of the Kalgoorlie School of Mines, and by 

 Mr. T. Blatchford and Mr. C. de J. Grut. Mr. A. Gibb Maitland, 

 Mr. H. P. Woodward, and Mr. C. G. Gibson, of the Geological Survey 

 •of the State, were ever ready to give information as to the conditions 

 in other goldfields, and to lend specimens, slides, maps, and books. 

 The extensive series of analyses, made principally by Messrs. E. S. 

 Simpson, C. G. Gibson, & C. C. Williams, has been freely drawn 

 upon, and has obviated the necessity of spending much time on 

 analytical work. Without the painstaking labour that the pre- 

 paration of these analyses has involved, tbe conclusions of this 

 paper would lose much in value. Penologists can never under- 

 estimate the debt that they owe to cbemists, whose work makes 

 little show in proportion to the time spent upon it. 



Any success that I may have attained in unravelling the structure 

 of the field by the interpretation of the amphibolites is entirely 

 ■due to the experience gained by association with Dr. J. S. Elett, 

 P. U.S., both in the study of Scottish and Cornish epidiorites and 

 •amphibolites in the laboratories of the Geological Survey, and in 

 field-work in the Lizard District. 



VI. Postscript. [April 28th, 1913.] 



The manuscript of the main part of this paper was despatched 

 in the confident anticipation that a series of line-drawings and 

 photographs, wdiich were prepared in Kalgoorlie during 1910, 

 would be received from Dr. Maelaren in time to follow by an 

 •early mail. Dr. Maelaren has now written to say that they 

 have unfortunately been lost, and that, still more unfortunately, 

 the slides from which they were prepared are also missing. In 

 these circumstances, it is possible to present only a few figures 

 prepared from such slides as I possess in my own collection, in 

 which only the rarer or more obscure types of Kalgoorlie rocks 

 are represented. Fortunately, a recent mail has brougbt an 

 advance-copy of a bulletin on Kalgoorlie in which is included 

 ■a series of. clear photographs of representative Kalgoorlie rocks 

 by Mr. H. Piowley & Mr. C. G. Gibson. 1 Reference to these 

 figures and to those previously published by Mr. Larcombe will 

 be facilitated by the list given below: — 



Abbreviations: — A = Sinipson & Gibson, op.cit. 



33 = C. O. G. Larcombe, Proc. Austral. Inst. Mm. 

 Eng. vol. v, no. 2 (1911). 



1 E. S. Simpson & 0. G. Gibson, 'Contributions to the Study of tbe 

 Geology & Ore-Deposits of Kalgoorlie, East Coolgardie Goldfield ' Bull. 

 Geol. Surv. W. Austral, fro. 42. Dated 1912. but issued in 1913. 



