TABLE OF ANALYSES 



183 





J. 



II. 



III. 



IV. 



V. 



VI. 



VII. 



SiO.; 



63.45 

 0.07 



18.31 

 0.42 

 3.56 



None. 



65.65 



"l6.84' 

 1 4.01 



65.43 

 0.50 



16.11 

 f 1.15 

 1 2.85 

 0.23 

 1.49 

 0.03 

 0.40 

 5.97 

 5.00 

 0.13 

 0.78* 



66.60 

 0.76 

 15.05 

 1.07 

 4.42 

 Ti-ace. 

 2.21 



66.13 



0.74 



17.40 



} 2.19 



0.13 

 0.81 



59.78 



64 35 



TiO., 





ALU, 



16.36 

 f 3.08 

 1 3.72 



15 46 



FeA 



FeO 



} 7.50 



MnO 



CaO 



BaO 



2.93 

 0.13 

 0.35 

 5.15 

 5.06 

 Trace. 



2.47 



"0.13' 

 5.04 

 5.27 



2.96 



3.58 



MgO 



0..36 

 5.42 

 4.03 



' ' ' o".41 



0.04 

 5.60 

 5.28 



1.22 



0.69 

 5.01 

 5.39 

 CO., 0.75 

 1.58 



0.50 



KjO 



3 45 



Na^O 



3 28 



p,o.- 





Loss 



0.30 



0.30 



1.63 









99.73 



99.71 



100.18 



100.33 



99.54 



99.96 



99.84 



Specific gravity of number I is 2.717 at 20° centigrade. 



I. Augite-syenite (akerite), Loon lake, New York. Analysis by E. W. Morley.f 



II. Augite-syenite (akerite) from Diana, New York. Description and analysis 

 by C. H. Smyth, Jr., in this Bulletin, vol. vi, pp. 271-274. 



III. Syenite, mount Ascutney, Vermont. Petrographical data by R. A. Daly, 

 analysis by L. G. Eakins, in U. S. Geological Survey Bulletin no. 148, p. 68. 



IV. Akerite, Gloucester, Massachusetts. Description and analysis by II. S. Wash- 

 ington, in Journal of Geology, vol. vi, p. 798. 



V. Akerite, between Thinghoud and Fjelebua, Norway. Analysis by Mauzelins, 

 description by Brugger, in Zeitschrift fiir Krystallographie, vol. xvi, p. 46, 1890. 



VI. Syenite, Silver Cliff, Colorado. Description by Whitman Cross, analysis by 

 L. G. Kakins, in ]7tli Annual Report, U. S. Geological Survey, pai't ii, p. 281. 



VII. Banatite, Farsund, Norway. Description and analysis by Carl Fred. Kol- 

 derup, Bergens Museums Aarljog, 1896, p. 213. 



DISCUSSION 



The Loon Lake rock (column I) is composed of microperthite, angite, 

 h3^persthene, and quartz, with a little magnetite and oligoclase,and such 

 small amounts of apatite and zircon that they in no way affect the totals. 

 With this comparativel}' simple make-up it would seem an easy matter 

 to calculate tlie composition of the rock. It soon appears, however, that 

 the augite must be jieculiar, and that a wholly satisfactor}^ calculation 

 can not be made until it has been analyzed. It must be either very rich 

 in iron or alumina, or both, or else contain considerable alkali, but its 

 optical characters are not those of any known alkaline pyroxene. Further, 

 the available analyses of aluminous augites show that a high alumina 

 percentage usually implies a large content of ferric iron, which is mani- 



* Tnplude.s F, O.rijS ; CI, 0.05 ; FeS.,, 0.07. 



fThe great oliligntinn.s of the writer to Professor Morleyfor this iiniilysis are gratefiill\'a<'kiio\vl- 

 edged. 



