METEORITES OF NORTH AMERICA. 283 



COMPOSITION OF SOLUBLE SILICATES (CHIEFLY CHRYSOLITE). 



Si0 2 36. 88 



MgO 36. 40 



FeO 13. 62 



A1 2 3 C. 64 



Cr 2 3 1. 38 



CaO 0. 08 



100. 00 

 Ratio of 2RO:SiO„::1.9997:l. 



COMPOSITION OF INSOLUBLE SILICATES (CHIEFLY BRONZITE AND MONOCLINIC PYROXENES). 



Si0 2 56. 52 



A1.,0 3 3. 07 



FeO 6. 05 



MgO 29. 28 



CaO 2. 94 



CoO 0. 10 



NiO 1-45 



Na 2 0. 53 



K 2 0. 06 



100. 00 

 Ratio of RO : Si0 2 : : 1 : 1 .0148 . 



To place the alkalies in the pyroxenes, as is here done, is contrary to the usual custom, it being common to 

 assume that they are present as feldspars. But as no feldspars could be detected in the slides and as alkalies are known 

 to enter into the composition of pyroxenes in small amount, the conclusion here adopted seems the more reasonable 

 one. No attempt was made to differentiate the two pyroxenes chemically, as I know of no guide for this. The amount 

 of monoclinic pyroxene which can be seen in sections is very small, so that the above can practically be regarded as 

 bronzite. It may seriously be questioned, however, whether digestion in hydrochloric acid can be relied upon to 

 wholly separate the chrysolite and bronzite, for with longer digestion some of the bronzite is apt to go into solution, or, 

 with shorter treatment, some of the chrysolite may not be decomposed. Further investigation of this subject should 

 be made. 



Taking all the probable ingredient minerals of the rock into consideration, the following is perhaps the best esti- 

 mate that can at present be made as to its probable composition : 



Bronzite and monoclinic pyroxenes 47. 05 



Chrysolite 24. 74 



Limonite 10. 50 



Chromite 8. 83 



Troilite 5-24 



Schreibersite 0-23 



Nickel-iron 3. 31 



Oxides of cobalt and nickel 0. 10 



100. 00 



Here the limonite is probably of secondary or terrestrial origin and should perhaps be divided up about equally 

 between the nickel-iron and troilite in estimating the preterrestrial composition of the rock. The composition as 

 shown above of about one-half bronzite accords well with what one can observe after treating a section with hydro- 

 chloric acid so as to dissolve out the chrysolite, for an extensive framework made up of bronzite then remains. The 

 high percentage of chromite indicated by the analysis is also in accordance with observations made with the microscope. 



The resemblance of the meteorite to terrestrial peridotites is, as noted by Weinschenk, very marked, and the-con- 

 stant association both in terrestrial and extraterrestrial regions of the elements and minerals which compose rocks of 

 this class indicates laws of association which are not yet comprehended. 



Brezina 4 in 1904 changed his classification of the meteorite to veined intermediate chon- 

 drite (Cia). 



The meteorite is distributed but the larger part is in the Field Museum collection. 



