Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/514

 2. Notes on the Minerals of Strontian, Argyllshire. By Robert H. Scott, Esq., F.R.S., F.G.S.

When I first proposed to visit Strontian, in the year 1866, 1 consulted two well-known Scotch geologists as to my chance of picking up minerals there. The two authorities directly contradicted each other. One, who was a professed mineralogist, stated that he had spent three weeks there, and that nothing whatever new was to be found there. The other was more encouraging, and informed me that whatever I found was nearly sure to be new.

Greg and Lettsom enumerate a fair series of specimens from the locality ; but the experience I have gained as to their accuracy as regards Irish localities, leads me to be somewhat dubious of receiving all their statements as absolutely correct for out-of-the-way districts, such as Strontian.

The longest list a which has been printed is that given by Mr. Hall in his Mineralogical Directory, and it is as follows : —

Apophyllite. Calcite. Pyromorphite.

Asbestos. Galena. Sphene.

Baryte. Garnet. Strontianite.

Blende. Harmotome. Talc.

Brewsterite. Pyrites. Zircon.

This list contains no notice of the various feldspars, of which there are certainly two, Orthoclase and a clear anorthic feldspar, in the granite, or of the Hornblende and other pyroxenic minerals which occur in the syenites and crystalline greenstones of the district, and of which fine, though not perfectly crystallized, specimens, are easily to be had. Nor does it mention Natrolite in geodes in the trap- dykes, or Schorl, or either of the micas, white and black, although very large plates of the former are found on Ben Resipol associated, as usual, with the garnets for which that mountain is famous.

These latter minerals I have myself seen in situ. Furthermore there appear to be some doubtful species in the list ; of these would only enumerate three, Apophyllite, Talc, and Zircon. No analysis is given of any of the three from this locality in any of the recognized textbooks of Mineralogy. Apophyllite I have never detected among the gangue of the lead-mines. This of course does not prove much. Talc certainly does not occur anywhere near Strontian itself ; and although from the analogy between the geology of the district and that of Donegal, in Ireland, I might fairly expect to find it, I could never trace any beds which bore the slightest resemblance to those in which so much Talc and Steatite have been discovered in the north-west of Ireland. I myself believe that the name of Talc has been loosely given to the large plates of white mica to which I have alluded, an error in nomenclature so very common in collections of Cornish minerals.

As to Zircon I have searched for it most carefully, and can only say that, as Greg and Lettsom admit the crystals from Criffel said to be Zircon to be really Sphene, I believe a similar qualification might with advantage be given to the alleged occurrence of Zircon at Strontian, and that it is as yet not proven.