Vol. 55.] AND FOESTEKITE PKOM THE GLENELG LIMESTONE. 373 



Mineralogy of Scotland,'^ he traces the course of limestone ex- 

 tending from Totaig, at the foot of Loch Duich, across the Big Glen 

 and the Little Glen of Glenelg, to the lower slopes of Beinn a' 

 Chapnill, and he gives descriptions and analyses of many of the 

 minerals which he observed in the limestone. Among the minerals 

 described are the following : — Malacolite (with two analyses), 

 eahlite (with analyses), coccolite (with analysis), and totaigite (with 

 two analyses). He speaks also of the occurrence in the limestone of 

 mother minerals, among which are serpentine (of yellow, green, or 

 blue-black tints), a mica resembling the phlogopite of the granular 

 limestone of the Yosges, talc, tremolite, and amianthus. In rocks 

 either in or close to the limestone, he describes, in addition, 

 necronite (with analysis), balvraidite (with two analyses), and 

 a pale brown biotite (with analysis). Prof. Heddle noticed that 

 some of the serpentine had been formed by the alteration of 

 an augitic mineral. He does not, so far as we can ascertain, mention 

 the occurrence in these limestones of any mineral of the oli vine- 

 group, though he states that the totaigite — a serpentinous pseudo- 

 morph of rather doubtful character — was first considered by him 

 to be either chondrodite or danburite.^ 



Mr. Alexander Eoss ^ has described some of the minerals in the 

 limestone of Loch Duich and Glenelg. He speaks especially of the 

 asbestos-veins and serpentine-pieces, and appears to consider that 

 these pieces have been formed by the alteration of pyroxenes. He 

 describes also the position of the limestone as lying on the east of 

 the great line of earth-movement extending from Eriboll to Strome 

 ^erry. 



We are not aware that either forsterite or true spinel (MgO, 

 AI2O3) has hitherto been recorded in Scotland. Macculloch ^ 



1 Trans. Eoy. Soc. Edin. vol. xxviii (1878) pp. 197 & 453, and vol. xxix 

 <1879) p. 1. 



2 The following are the two analyses made by Prof. Heddle of totaigite : 

 .(1) of a pale fawn variety, and (2) of a blue-black variety, which weathers with 

 a soft, serpentinous, ochre-yellow surface : — 



(1) (2) 



SiOa Silica 37-221 36'193 



AI2O3 Alumina '757 '264 



FeaOg Ferric oxide -286 



FeO Ferrous oxide 1-045 2-958 



MnO Manganous oxide -230 '454 



CaO Lime 5243 3*272 



MgO Magnesia 44-973 45-570 



K2O Potash -252 



Na^O Soda -424 



H2O Water 10-643 10-200 



100-112 99-973* 



* This analysis is reprinted as it appears in Prof, Heddle's description, but 

 there must be some mistake in it. The figures of the different constituents add 

 «p to 99-873. 



^ 'Asbestos near Loch Duich,' Trans. Inverness Sci. Soc. & Field Club 

 lyol. iv, p. 49. 



* ' Western Is. of Scotland,' vol. i (1819) p. 56. 



