COMPOSITION AND STRUCTURE OF METEORITES 



47 



Constituent 



III 



Silica (SiOs) 



Titanic oxide (Ti02) 



Tin oxide (SnOs) 



Zirconium oxide (ZrOs)..- 



Alumina (AI2O3) 



Ferric oxide (FeaOa) 



Chromic oxide (Cr203) 



Vanadium oxide (V2O3)--- 



Metallic iron (Fe) 



Metallic nickel (Xi) 



Metallic cobalt (Co) 



Ferrous oxide (FeO) 



Nickel oxide (NiO) 



Cobalt oxide (CoO) 



Lime (CaO) 



Barium oxide (BaO) 



Magnesia (MgO) 



Manganous oxide (MnO). 



Strontium oxide (SrO) 



Soda(Na20) 



Potash (K2O) 



Lithia (Li:0) 



Ignition (H2O) 



Phosphoric acid (P2O5) --. 



Sulphur (S) 



Copper (Cu) 



Carbon (C) 



Chlorine (CI) 



Carbonic acid (CO2) 



Fluorine (F) 



38.41 



.16 



None. 



None. 



2.86 



.92 



.40 



Trace. 



12.35 



1.09 



.10 



13. 60 



.40 



.06 



1.88 



None. 



23.66 



.23 



None. 



.82 



.16 



Trace. 



.47 



.34 



1.89 



.01 



.16 



.03 



(?) 



(?) 



100. 00 



37.78 

 .58 



3.11 



2.41 



.19 



18.36 

 .18 



28.38 

 .31 



.68 

 .32 



3.79 

 .10 



100.00 



59. 93 

 .74 



.03 



14. 97 



2.58 



.05 



.02 



3.42 

 .03 



4.78 

 .11 



3.85 

 .10 

 .04 



3.40 



2.99 

 .01 



1.94 

 .26 

 .11 



.06 

 .48 

 .10 



The most important of the differences brought out by the analyses 

 are (1) the excess of silica (Si02) and alumina (AI2O3) in the terrestrial 

 rocks; (2) the presence of a considerable amount of free iron and 

 proportionately large quantities of ferrous oxide (FeO) and mag- 

 nesia (MgO) in the meteorites. The presence of many of the rarer 

 elements tabulated as constituents of the terrestrial igneous rocks 

 has not yet been fully established in those of meteoric origin. As 

 noted, however, many of them have been found in amounts too small 

 to estimate.' Here indeed is a striking thought — that throughout 

 all space so far as yet made known to us, there exists so great a uni- 

 formity of material yet so individualized that one conversant there- 

 with can tell almost at a glance whether celestial or terrestrial in 



origm. 



TEKTITES 



Of late years there has been much discussion relative to the possible 

 meteoric nature of certain glass pebbles of a green or black color 

 with peculiar markings, found on the immediate surface or slightly 

 embedded in Tertiary and Quaternary gravels in Australia, Moldavia, 

 islands of the Malayan Peninsula, and a few other localities. The 

 Australian forms, variously known as "bombs," "obsidian buttons," 

 "australities", etc., are of a dense black glass, rounded, irregularly 



5 Merrill: The composition of stony meteorites compared with that of terrestrial igneous rocks, and 

 considered with reference to their efficacy in world making; Amer. Journ. Sci., ser. 4, vol. 27, 1909, p. 469. 

 Also: Report on researches on the chemical and mineralogical composition of meteorites, with special 

 reference to their minor constituents. Mem. Nat. Acad. Sci., vol. 14, memoir 1, 1916. 



