2 10 SMITHSONIAN MISCELLANEOUS COLLECTIONS [vOL. 45 



• It will be noted that the analyses show rather wide discrepancies, 

 only . the wide ranges in the ratios involved in the c^ssificatory 

 scheme allowing them to be placed in similar subdivisions ; thus, 

 for example, in the Greenland rock, the ratio Q :F is 0.6, in the 

 graphic granite from Omeo it is 0.22. The ratio between the 

 alkalies and lime in the former case is 15.5, and that between the 

 potash and soda is 1.9; these respective ratios in the type omeose 

 being 30 and 4. 



Diorite (Cat. No. 75,481). — The diorite has been described as 

 forming a series of horizontal dikes in the g»anite and as varying 

 in texture from a very fine grain to a pegmatitic facies. The lower 

 dike material has been chosen as a type of the magma, from which 

 all the diorites have come for the reasons stated on page 190 of 

 this article. Its analysis, therefore, is given with that of von 

 Lasaulx's doleritic lava from Auvergne, the diorite having worked 

 out to an auvergnose. 



Analyses of Diorite — Auvergnose 



(i) (2) 



SiO,. 47.80 48.57 



AI2O:! 18.24 19.47 



Fe.03 35 ^- 



FeO 9.27 13.53 



MgO 8.08 4.25 



CaO 11-44 10.86 



NhqC 2.24 1.33 



K.0 ' .45 .82 



HjO above 100° 58 



H2O below 100° ■ — ( 



Ti02 1.46 — 



P=05 24 — 



MnO -55 76 



100.70 100.07 



Note. — i. Diorite (Auvergnose) Greenland, W. C. Phalen, analyst. 2. 

 Doleritic lava from Auvergne, A. v. Lasaulx, analyst. Neues Jahrbuch f. 

 Mill., Geol. u. Pal, 1869, p. 657. 



Composition in Terms of Standard Minerals 



(I) (2) 



Orthoclase 2.78 5.00 



Albite 18.86 I i.oo 



Anorthite 38.09 44-76 



Ilmenite 2.89 ' — 



Magnetite 70 — 



Apatite 31 — 



Diopside 14-56 7.83 



Hypersthene 5.01 25.62 



Olivine 16.961 5.45 



H=0 ^58 .48 



100.77 100.14 



