14 



BULLETIN 9i, UNITED STATES NATIONAL MUSEUM. 



composition of stony meteorites as calculated from a large number 

 of analyses/ and in column II that of the average composition of 

 the igneous rocks of the earth's crust.^ 



It may be added incidentally that these meteoric stones, as will be 

 noted from the analyses, belong to a very basic class of rocks — i. e., 

 rocks low in silicic acid and correspondingly high in the basic con- 

 stituents, iron and magnesia. From a terrestrial standpoint they 

 would be classified mainly as peridotites, and a few as pyroxenites 

 and basalts. 



Constituents. 



Silica (SiOz) 



Titanic oxide (TiOj) 



Tin oxide (SnOj) 



Zirconium oxide (ZrOj) . . 



A lumina ( AljOj) 



Ferric oxide (Fe203) 



Chromic oxide (Cr203) - . - 

 Vanadium oxide (V2O3). - 



Iron(Fe) 



Nickel (Ni) 



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(K20) 



Lithia (LizO) 



Ignition (H2O) 



Phosphoric acid (P2O6) . . 



Sulphur(S) 



Copper (Cu) 



Carbon(C) 



Chlorine(Cl) 



Fluorine(F) 



Carbonic acid (CDs) 



38.68 



.18 



None. 



None. 



2.88 



.47 



Trace. 



11.98 



1.15 



.07 



14.58 



.48 



.06 



2.42 



None. 



22.67 



.29 



None. 



.87 



.21 



Trace. 



.75 



.26 



1.80 



.014 



.15 



.08 



(?) 



CI) 



100.044 



U. 



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 

 .10 

 .48 



The most striking of the differences brought out by the analyses 

 are (1) the excess of silica (SiOg) and alumina (AljOg) in the 

 terrestrial rocks, (2) the presence of a considerable amount of free 

 iron and proportionately large quantities of ferrous oxide (FeO) 



1 Merrill, On the composition of stony meteorites, etc., Amer. Journ. Sci., vol. 27, June, 

 1909, p. 469. 



« Clarke, Data of Geochemistry, Bulletin 491, U. S. Geol. Surv., 1911, p. 27. 



