202 



THE MAK(,)UETTE lEON-BEAElNG DISTEICT. 



A schist iiiav therefore have any composition within a very wide range, 

 and, akhougli this composition may be identical with that of some slate, or 

 even with the mean composition of many slates, the rock ma}^ nevertheless 

 be a verv slightly altered granite. 



Three analvses of the micaceous schists, one complete and two par- 

 tial, have been made (Analyses IV, V, and VI). These are compared 

 witli an analysis of Cambrian slate from j\Ielbourne, Province of Quebec 

 (Analysis I), and with analyses of the amphibole-granitite from Hoh- 

 wald (Analvsis III) and the granitite from Landsberg, in the Audlau 

 (Analvsis J I). As will be seen, the two granites vary in the proportions 

 of the alkalis and the alkali earths present, the Hohwald rock containing 

 but 4 per cent of the former, while the Andlau rock contains 7 per cent.* 

 In eacli, CaO exceeds ilgO in quantity. The composition of the slate 

 is not verv different from that of the granites except in one particular— 

 the percentage of MgO present is over five times that of the CaO. 



Analyses of slate, (jraniiites, and schists. 



I. Cambrian slate from Melljourue, Quebec, .\nalyst, T. S. Hunt. Am. Jour. Sci., 3d series, 

 Vol. L, 1895, p. 67. 



II. Granitite from Laudsberg, near Barr. Analyst, Ur. H. Unger. H. Rosenbusch, Die Steiger 

 Schiefer, etc., 1877, p. 147. 



III. AmpUibole-grauitite from Hohwald. Analyst, Dr. H. Unger. H. Rosenbusch, Die Steiger 

 Schiefer, etc., p. 167. 



