76 Professor Necker on some rare Scottish Minerals. 



Carsaig, in the island of Mull, and of Lamlash, are also of 

 Gallinace, The Gallinaces present the same relations to the 

 basalts, as the pitchstones do to the trappean and felspathic 

 porphyries, the vitreous lavas to the compact, and the obsi- 

 dians to the trachytes. The gallinaces are vitreous basalts, 

 while the pitchstones are vitreous felspathic traps. 



4. Green diopside is found in the upper part of the valley of 

 Beal. It is of an impure green tint, is very translucent, pre- 

 sents a form analogous to that of augite, and replaces the 

 common augite in a large grained basalt, being often mixed 

 with a bluish calcedony. 



5. Levyne^ in small crystals, similar to the form figured in 

 Allan'^s edition of Phillips' Mineralogy, of a milk-white colour, 

 and semi-translucent or opaque, occurs in cavities in the beau- 

 tiful basaltic amygdaloid of the Storr in Skye, and in the whole 

 basaltic northern portion of the island ; also at Quiring. In 

 both these localities, the chabasite and levyne are always se- 

 parate. I have only seen one or two cases where isolated 

 crystals of chabasite were found in the cavities occupied by the 

 levyne, and I have never seen the levyne in those of chabasite. 



6. Lumachella marhle, analogous to that of Bleyberg in 

 Carinthia, is met with at Loch Shiant, on the west side of 

 Loch Staffin, in Skye. The pieces of ammonite, of a high 

 lustre and brilliant colour, which give it the peculiar charac- 

 ter, are of rare occurrence, and the bed in which they are met 

 with is below high water-mark. 



7. Very large portions of mica are found in Glen Shiel, 

 near the road leading from Glenelg to Fort Augustus, and 

 about half-way between the inns of Shiel House and Cluny. 

 The plates are nine inches in length by six in breadth, and 

 three-fourths of an inch in thickness ; but, as I did not pro- 

 cure them myself, I cannot say if they are found in the gneiss 

 itself, or in granite veins. There are on the surfaces very dis- 

 tinct traces of cleavage, forming strise arranged in equilateral 

 triangles, as in specular iron-ore ; a circumstance which would 

 have led me to believe it to be uno-axial or rhomboidal, but 

 an experiment made along with Professor Forbes proves it to 

 be diaxial or prismatic. 



8. Garnets. — The talc or chlorite slate of the Glen Shant 



