of the Buchan District. 103 



character to be seen. I have not observed any crystals of 

 mica, or of hornblende, nor any alteration products which I 

 could refer to those species, unless it were some slight traces 

 of chloritic minerals. 



This rock may, with some reasonable certainty, be referred 

 to the quartz porphyrites, and I feel little doubt that it 

 represents the former condition of the " red rocks" which I 

 have just before described. 



The Diabase Rocks. — Resting upon the red porphyrites 

 there is a considerable thickness, perhaps 200 feet, of Diabase 

 rocks. The lowest of these lies on the porphyrites, but I 

 cannot feel sure that they are entirely conformable in dip to 

 them. 



The lowest Diabase rocks which I could examine are 

 those indicated at (d), and they are a good example of the 

 Diabase tuffs of the district, containing also rounded frag- 

 ments of the underlying red porphyrites. These tufas are 

 so friable and so much altered that none of the samples I 

 collected would admit of a thin slice being prepared for 

 examination. 



It is in a continuation of these fragmental beds that the 

 adit of the now long-defunct Murendel South Mining Com- 

 pany was driven, at the place where the beds are cut off by 

 a strong north and south nearly vertical fault, which I have 

 shown on the diagram by (x). 



The heaps of stuff brought out of this adit during the 

 time it was being worked show that the rocks adjoining the 

 fault are much more altered than those at a little distance, 

 and that they have been slightly enriched by deposits of 

 lead and copper, and massed together by a good deal of red 

 jasper and chalcedony. 



The rest of the Diabase upwards from (c) consists of bands 

 of various texture, some being fragmental and others compact. 

 The latter show along the steep hill sides in several strongly 

 marked outcrops. 



I collected samples from the beds marked (b) and (c) and 

 also at the place (h). 



On examining thin slices I found all to have the well- 

 marked characters of the Diabase porphyrites, as described by 

 me in the previous paper. All that I need note is that 

 enstatite is rare, seemingly, as I found it only in one slice, 

 and that the samples taken from (c) near the fault contain 

 olivine. These samples are much altered, and the olivine 

 is converted more or less into a translucent^ red micaceous 



