CHEMICAL COMPOSITION OF SEPULCHRE MOUNTAIN ROCKS. 135 



CHEMICAL COMPOSITION. 



The chemical composition of the eruptive rocks of Sepulchre Moun- 

 tain is shown in the accompanying table of chemical analyses : 



Table XIV. — Chemical analyses of rocks from Sepulchre Mountain. 



Constituent. 



421 



471 



407 



386 



409 



487 



494 



521 



523 





55.83 



1.05 

 17.11 

 4.07 

 3.75 

 None. 

 7.40 



55.92 



.94 



17.70 



3.16 



4.48 



Trace. 



5.90 



56.61 



.79 



13.62 



5.89 



2.60 



.35 



6.61 



.14 



5.48 



Trace. 



3.13 



2.71 

 .06 



(?) 



None. 

 2.27 



57.17 

 1.03 



17.25 



2.48 



4.31 



None. 



6.61 



4.83 



Trace. 



3.44 



2.03 



.05 



Trace. 



Trace. 



1.20 



60.30 



.76 



16.31 



4.35 



1.41 



.13 



5.62 



.15 



2.39 



Trace. 



3.99 



2.36 



.20 



.10 



None. 

 2.50 



64.27 

 .32 



17.84 



3.36 



1.29 



None. 



3.42 



2.00 



.03 



3.84 



2.48 



.16 



Trace. 



None. 



1.32 



65.50 



.45 



14.94 



1.72 



2.27 



.20 



2.33 



.13 



2.97 



Trace? 



5.46 



2.76 



.09 



.06 



None. 

 1.37 



65.66 

 1.37 



15.61 



2.10 



2.07 



None. 



3.64 



67.49 



.13 



16.18 



1.30 



1.22 



.08 



2.68 





A1 ; 3 



Fe.,0 3 



FeO 



MnO 



CaO 



BaO 



MgO 



5.05 



4.34 



2.46 



1.34 



SrO 



Li 2 



None. 



2.94 



1.71 



.21 



Trace. 



None. 



.09 



4.08 



2.28 



.18 



Trace. 



None. 



.36 



3.65 



2.03 



Trace. 



.13 



.12 





K 2 



4.37 



2.40 



.13 



p.,o 6 



S0 3 



CI 





CO, 





H 2 



1.28 



1.42 



1.07 



2.69 



Less O for CI. 



100. 40 



100. 45 



100. 26 



100. 40 



100. 57 



100. 33 



100. 25 



100. 27 

 .03 



100. 01 

















100. 24 



Nos. 421, 471, 386, 487, and 521 were analyzed by Mr. J. E. Whit- 

 field; Nos. 407, 409, and 494 were analyzed by Dr. T. M. Chatard; and 

 No. 523 was analyzed by Mr. L. G. Eakins. 



The first, 421, and the fourth, 386, are analyses of pyroxene-andesites 

 which carry no hornblende. The first is from a dike near the summit of 

 the mountain; the other is from a surface flow at its southwest base. 

 Nos. 407 and 409 are of hornblende-pyroxene-andesites, occurring as 

 breccia in the upper part of the mountain. No. 471 is of hornblende- 

 andesite, which is an intruded body in the small hill northeast of Cache 

 Lake, at the head of Reese Creek. No. 487 is a hornblende-mica-andesite 

 from the same locality, also an intrusive rock. No. 494 is the same kind of 

 andesite from an intrusive mass at the north base of Sepulchre Mountain, 



