METEORITES OF NORTH AMERICA. 175 



From the edge of side F, which shows comparatively slight oxidation, three indistinct veins run into the meteorite. 

 They are black, indefinite in outline, and somewhat branching. 



A petrological analysis by W. Harold Tomlinson of Germantown, Pennsylvania, shows that the mineral constituents 

 are olivine and enstatite. Some pyrrhotite was also found. Mr. Tomlinson remarks: "The olivine and enstatite occur 

 both as grains and as chondri. The grains of olivine contain frequent inclusions of smaller grains and of iron, and 

 occasionally have gaseous inclusions. The inclusions in the enstatite are generally parallel to the cleavage." He 

 found the specific gravity to be 3.60. 



CHEMICAL ANALYSIS BY JOHN M. DAVISON. 



The specific gravity of the Estacado aerolite is 3.63. The metallic part was separated with a magnet and the slight 

 amount of adhering stony matter determined and deducted. 



The stony part was separated by hydrochloric acid into a soluble and an insoluble portion. The insoluble portion 

 waa digested with a solution of Na 2 C0 3 and the dissolved SiO, added to that dissolved by HC1. This analysis gave: 



Metallic 16. 41 



Stonv J Soluble in HCI 41 - 09 



" {insoluble in HCI 42.50 



100.00 

 Analyses of these, omitting minor constituents and calculated to 100, gave: 



Metallic. Soluble in HCI. Insoluble in HCI. 



Fe S9.45 SiO, 32.00 Si0 2 63.57 



Ni 9.99 MgO 32.02 MgO 23.45 



Co 0.56 FeO 31.60 FeO 9.54 



CaO 4.38 CaO 3.44 



Km on 



100. 00 100. 00 



The stony part appears to be mainly olivine and enstatite. The analysis of the entire mass gave the following 

 percentages: 



Fe 14. 68 



Ni 1.60 



Co 0.08 



Cu Trace. 



C (found but not determined). 



S 1.37 



P 0.15 



SiO, 35. 82 



FeO" 15.53 



MgO 22.74 



CaO 2. 99 



AL0 3 



K 2 



TiO,, Cr,0 3 , and MnO (found but not determined). 



Less O for S 



100. 27 



Of the S found 0.82 per cent came from the metallic and the portion soluble in HCI, and 0.55 per cent from the 

 insoluble portion fused with Na 2 C0 3 . In this fusion the crucible was screened by a close fitting asbestos board and a 

 blank experiment showed that there was no contamination from the gas flame. This distribution of the S would 

 indicate that nearly half of the troilite was embedded in the enstatite protected from action of acids. 



From 3.9597 grams of the aerolite 0.025 gm. of chromite was separated by repeated treatment with HF and other 

 acids. With the chromite were a few minute particles of a transparent colorless mineral that had survived this usage 

 though evidently attacked. Search was made for Zr0 2 , with negative result. 



BIBLIOGRAPHY. 



1. 1906: Howard. Estacado aerolite, preliminary notice. Amer. Journ. Sci., 4th ser., vol. 21, p. 186. 



2. 1906: Howard and Davison. The Estacado aerolite. Amer. Journ. Sci., 4th ser., vol. 22, pp. 55-60 (analysis 



and illustrations). 



