196 ARNOLD AND STRONG — CRYSTALLINE ROCKS OF SAN GABRIEL 



Table of analyses of granodiorites 





I. 



A. M. S. 



number 10, 



mount 



Wilson. 



II. 



A. M. S. 

 number 12, 

 Pine flats. 



III. 



H. W. T. 



number 17, 



Sierra 



Nevada. 



IV. 



W. L., 



Sierra 

 Nevada. 



V. 



Limits 



of 



variation. 



VI. 



Average 

 composi- 

 tion. 



Si0 2 



Ti0 2 



61.38 



64.45 

 Trace 



17.18 

 1.31* 

 2.61* 

 1.62 



63.43 

 0.73 



14.20 

 1.54 

 4.56 

 0.03 

 0.06 

 5.51 

 2.35 

 2.19 

 3.49 

 1.65 

 0.11 



65.54 

 0.39 



16.52 

 1.40 

 2.49 

 0.06 



Per cent 

 59-69 



Per cent 

 65. 



A1 2 3 



14.33 

 2.50* 

 6.16* 



Trace 



14-17 



1M* 



16. 



Fe 2 3 



FeO 



1.50 

 3. 



MnO 





BaO 







CaO 



MgO 



5.42 

 2.98 

 2.58 

 4.71 

 0.13 



4.31 

 0.75 

 2.98 

 4.24 

 0.59 

 Trace 



4.88 

 2.52 

 1.95 

 4.09 

 0.59 

 0.18 



3-6| 



1-2* 



l-3f 



2*-4§ 



5. 



2. 



K 2 



2.25 



Na 2 



H 2 



3.50 



P„0, 



(Remainder 1.75) 









100.19 



100.04 



99.85 



100.61 





100.00 



*See notes under same analyses on previous pages. 



LA. M. S. number 10, mount Wilson, San Gabriel mountains, Los Angeles 

 county. A. M. Strong, analyst. 

 II. A. M. S. number 12, Pine flats, San Gabriel mountains, Los Angeles county. 

 A. M. Strong, analyst. 



III. H. W. T. number 17, Smartsville area, 2 miles northeast of Bangor, Sierra 



Nevada mountains. W. F. Hillebrand, analyst. (H. W. Turner, 17th 

 Annual Report U. S. Geol. Survey, pt. i, 1896, p. 724.) 



IV. W. L., Sierra Nevada mountains, Lincoln, Placer county, Sacremento folio. 



W. F. Hillebrand, analyst. (W. Lindgren, American Journal of Science, 

 vol. ix, April 1900, p. 273.) 

 V. Limits of variation for granodiorite. (W. Lindgren, loc. cit., p. 272.) 

 VI. Average composition of granodiorite. (W. Lindgren, ib. cit.) 



Comparing the analysis of A. M. S. number 10 with Lindgren's limits 

 of variations for granodiorite, it is seen that the Mount Wilson rock is 

 rather low in Si0 2 , but high (to excess, according to the limits given in 

 the table) in Fe 2 8 , FeO, MgO, and Na 2 0. Disregarding the latter two, 

 which are only slightly above the limit, it is evident that the iron shows 

 the only great discrepancy. This is accounted for partially by error in 

 the analysis (see previous notes), but mostly, however, by the large 

 amount of hornblende in number 10. The hornblende also accounts 

 for the high percentage of magnesium and soda. No titanium was dis- 

 covered in the analysis of number 10, and no titanite was seen in its 



