14 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
Mineralogical works, again, present us with three “dark magnesian-micas,” 
—phlogopite, Biotite, lepidomelane. Mineralogical works, one and all, are 
unsatisfactory as regards the amount of information they convey as to the 
habitudes of minerals,—their lithological habitats. 
Phlogopite there is some precision as to; it is said, to be “ especially 
characteristic of serpentines, and crystalline limestone, or dolomite.” Biotite, 
or the micas placed under that heading, would, on the authority of said works, 
appear to occur almost everywhere. Lepidomelane is given as occurring in 
syenite, granite, and quartzite. 
Dr Haucuton has imported some precision into this question, as regards the 
dark granitic-mica, so far as Ireland is concerned ; but the conclusion he arrived 
at does not, singularly enough, apply to Scotland. And again, while I have 
not yet met with a single specimen of phlogopite in Scotland, I find that it 
must, as regards this country, be said of Biotite, and not of phlogopite, that it 
is “specially characteristic of crystalline limestones,” seeing that, with the 
exception of margarodite, and it only rarely, I find no other mica in that 
rock. 
The dark magnesian mica, which, in Scotland, is specially characteristic of 
granites, will be shown to be a new, or at least an unrecognised species. 
PHLOGOPITE. 
I have not yet, by analysis, been able to show that phlogopite occurs in 
Scotland. 
The light-brown Biotite from the limestone of Shinness—the analysis of 
which is given below—is in appearance very similar to some foreign phlogo- 
pites; but upon this proving to be Biotite, all resembling it which were not 
analysed were considered to be Biotite also. 
In specimens of granular limestone from the Vosges, there is a mica named 
phlogopite by Professor Kine, which is so similar to the limestone-mica of Glen 
Elg, that it is possible that the latter may prove to be this most highly magnesian 
species. It however occurs in so small an amount in the lime, thata spec ial 
visit to the locality could alone ensure a sufficiency for analysis. 
