Experimental researches on the granites of Ireland / by Samuel Haughton.

  • Haughton, Samuel.
Date:
1858
Catalogue details

Licence: Public Domain Mark

Credit: Experimental researches on the granites of Ireland / by Samuel Haughton. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    7/8 (page 305)
    From the tact that the atoms of protoxides exceed the atoms of })er- oxides, it appears that this elvan cannot be composed of qnartz, felspar, and green mica. If we suppose that hornblende replaces mica in this elvan, and that half the iron is present as protoxide, and that all the alkalies belong to the felspar of the rock, it is easy to calculate the fol- lowing Mineralogical Composition of the Soda-Elvan. Quartz =29-52 Felspar ..=60-15 Hornblende^ 8 81 98-48 From the discussion of the granites of the potash- and soda-type in this district, I feel disposed to draw the following conclusions, which are confirmed in a remarkable manner by some observations I have recently made, in conjunction with Mr. Jukes, in the County Wicklow :— 1st. That both in Leinster and the county Down, the potash-granites are more constant .in composition, both mineralogical and chemical, than the corresponding soda-granites. 2ndly. That the potash-granite appears to be the standard type of granite, from which other granites and crystalline rocks are formed by the addition of bases ; for example, the anorthite syenite of Car- lingford, and the soda-granites of Newry, and in Leinster the out- lying patches of granite between the main chain and the sea. 3rdly. That the potash-granite of Leinster is more persistent in external character than the potash-granites of Newry, although the latter are equally constant in chemical composition.