112 



THE UNIVERSITY OF OKLAHOAIA 



tions are compared with those of E. P. Rothrock in the following 

 table : 



Tabulation of Minerals in the Black Mesa Basalt 



Species 



p; 



Laboradorite 



Laboradorite 



Pyroxene 



Augite 



Magnetite 



Magnetite 



Olivene 



Olivene 



ize .n 

 Mill.'meters 

 n. d. 

 0.2 

 n. d. 



0.1 to 0.2 mm 

 n. d. 



.099 mm. 

 1.3 mm. max. 

 0.425 mm. 



Observer 



Shead 

 Rothrock 



Skead 

 Rothrock 



Shead 

 Rothrock 



Shead 

 Rotl:rock 



Amount in Rock 

 in Percent 



45.0 



45.0 



45.0 



45.0 



9.0 to 9.5 



7.0 



0.3 



1.0 



Intimately related to the mineralogical composition of the 

 basalt is the chemical composition shown by the following analysis 

 made by the writer : 



Analysis of Black Mesa Olivine Diabase 

 The sample consisted of several chips taken from an SOD pound 

 specimen of Black Mesa collected in the summer of 1919 by E. P. 

 Rothrock of the University of Oklahoma. This specimen is to be 

 exhibited at the Oklahoma State Fair at Oklahoma. 



Percent 



SiO,— Silica 50.96 



Al^Og— Alumina 17.54 



Fe^Og — Ferric oxide 3.10 



FeO — Ferrous oxide 7.46 



Mgo — ^Magnesia __ 5.17 



CaO — Calcium oxi^e 9.18 



Na.,0 — Sodium oxide 2.78 



.54 



.48 



.38 



1.31 



ZrO., — Zirconia (Probably absent) n. d. 



K^O — Potassium ox'de 



H'.O— Water belowvv 110° C. 

 H.,0 plus — Water above 110° 

 TiO„- — Titanium oxide 



CO., — Carbon dioxi'le Faint 



P.,0, — Phosphorous pentoxide 



SOy — Sulphur trioxide 



rci. F) 



.; — ouipnur . . 



Cr,0, — Chromium oxide _____ 



v;o; ZZI~r' 



>rO— Oxide of nickel 



Trace 

 .54 

 .00 



n. d. 

 .08 

 .04 



n. d. 

 .00 



