250 Dr. Heddle and Mr. R. P. Greg on British Pectolites. 



The specific gravity of the fibrous variety is 2*881, and our 

 analysis on 25 grains is given under c ; that of the crystals taken 

 on 5 grains is given under d. 



98-995 99-844 



About three years ago Mr. M'Gibbon found a mineral at 

 Kuockdolian Hill, near Ballantrae in Ayrshire, the matrix of 

 which was limestone. 



Its specific gravity is 2-778, and our analysis, made on 25 grains, 

 is given in the Table, No. 8 ; and this mineral is therefore pec- 

 tolite. At this locality it also occurs in needle crystals. 



Some time ago we got this mineral from Talisker in Skye 

 associated with mesotype and stilbite ; the analysis is No. 9. 

 Dr. Scott of Edinburgh has analysed this mineral, with results 

 differing in the soda and the water, the quantity of the former 

 being 7-670, and of the latter 5*058 (see No. 10). 



Our last locality is on the shore near Girvan in Ayrshire, 

 where the mineral occurs in quantity, and of considerable beauty, 

 hitherto known to collectors as white tremolite; here it varies 

 from highly translucent and fibro-crystalline to opake, being 

 sometimes, however, as tough as the okenite from Faroe. 

 Our analysis on 25 grains afforded, — 



Silica .... 53-480 

 Alumina . . . "055 



Oxide of iron . . -005 



Lime 34*384 



Magnesia . . . traces 



Soda 9-877 



Potash ..... '355 

 Water .... 3-262 

 The mineral is apparently purer at this locality than at any 

 other. 



We have pectolite occurring in Scotland at the following loca- 

 lities : Kilsyth, Costorphine Hill, Loch End, Edinburgh Castle, 

 Ratho, Kuockdolian Hill and Girvan in Ayrshire, and at Talisker 

 in Skye : and we now have analyses of specimens from all these 

 localities, with the single exception of Loch End*. Specimens 



* According to Prof. It. D. Thomson, pectolite has occurred also at 

 Bishoptown, and near Kilpatrick. 



