154 TF. Campbell SniitJi, — Borolanite from Moss-shire. 



In the same paper Dr. Shand gives a sketch-map of the district, 

 and a brief description of the positions of various localities mentioned 

 above may not be irrelevant. 



The main mass of rocks occupies about 5 square miles between 

 Ledbeg and Loch Borolan, attaining its greatest height at Cnoc-na- 

 Sroine, east of the former locality. Aultnacallagach is situated on 

 the north-east of Loch Borolan, and the main exposures of borolanite 

 occur in the stream Allt a' Mhuilin, to the south-east of this place. 

 Am Meallan is on the roadside, close to Allt a' Mhuilin and slightly 

 to the north-west. It should also be noted that Camas Eilean Ghlais, 

 where the dyke-rock occurs, is on the coast about 18 miles west of 

 Loch Borolan. 



A summary of most of the work above mentioned is given in the 

 Memoir of the Geological Survey of the North-West Highlands. 



At the suggestion of Mr. R. H. Rastall an analysis of a borolanite 

 from Am Meallan has been made. The specimen, kindly provided by 

 Mr. Harker and collected by him a few years ago, was dark grey 

 in colour, with numerous ill-defined white patches, which never 

 exceed 1 cm. in diameter. The groundmass was fine-grained, the 

 garnets being very small. Some lath-shaped cleavage faces of felspar 

 were observable. 



To obtain a good average sample about 400 gms. of rock was 

 coarsely powdered and well mixed; about 100 gms. of this was then 

 more finely powdered, and finally about 10 gms. ground down for 

 analysis. Silica and the bases were estimated on about 1 gm. of 

 substance, alkalies and ferrous iron being each estimated on 

 a separate quantity of about '5 gm. Water was determined on 

 about 1 gm. of powder, contained in a platinum boat and heated 

 in a quartz tube, first by a Teclu burner and finally by a strong blast. 

 The water was collected in a weighed sulphuric acid tube. The loss 

 in weight of the boat was in each case slightly less than the weight 

 of water collected, owing to the presence of Fe 0. For the rest the 

 directions of Washington and Hillebrand were folloAved throiighout. 

 The results were as follows : — 



Sp. gr. = 2-77. 



Traces- of P^ O5 and Mn were also present. 



