GEOLOGY OF THE SAN JOSE DISTRICT 285 



Two analyses of the analcite tinguaite are given below. 



I. II. 



SiO., 52.83 49-42 



TiOa 16 



AI2O3 20.70 22.99 



FeA 2.84 2.70 



FeO 1. 19 1.89 



MgO 41 .45 



CaO 1. 00 2.59 



Nap 9.94 9.63 



K2O 4-87 4.21 



H2O110 37 



Ufi^Sn 5.28 5.73 



P205 03 



CI 06 



99.62 99.99 



I. Analcite tinguaite, San Jose, Tamaulipas, Mexico. H. S. Washington, anal. 



II. Analcite tinguaite, San Jose, Tamaulipas, Mexico. G. I. Finlay, anal. 



The calculation of I results as follows in percentage compo- 

 sition by standard minerals : 



Orthoclase 28.9 Acmite 4.2 



Albite 25.7 Diopside 4.2 



Nephelite 29.0 Magnetite 2.1 



Sal 83.6 Fern 10.5 



The rock, therefore, belongs to order 6 russare of the per- 

 salanes. It is peralkalic miaskase and dosodic miaskose. 



Number II gives the following mineral percentages for its 

 norm : 



Orthoclase 25.02 Magnetite 3-94 



Albite 19-91 Diopside 4.86 



Anothite 7.23 Fern 8.80 



52T6 



Nephelite 33-23 



Sal 8^39 



It is tasmanare order 7 of the persalanes. It is peralkalic 

 laugenase and dosodic laugenose. 



3 . Camptonite 

 ia) San Carlos Type. — Numerous small dikes of this rock 

 are found in the more basic portions of the nephelite syenite 



