198 Fretp Museum or Natural History — Geo oey, Voz. III. 
Leucite, K, 0: Als O03. 4001 OF; Rees eee ee I¢ 
Nephelite, Naz O'. AleOs3% 2:51 Os en een ees ne L 
Kaliophilite; Ks O . Als O22 S51 Os epen ee err ee kp 
GROUP II: FEMIC MINERALS 
Acmite, Nag 0 5 Fes Ox t Avat Osee a een ee ee ac 
Sodium: metasilieate, Nas Oi .51 Oi... ee ee ns 
Potassium metasilicate, Ka Or Oni ee ee ks 
Diopside’ Ga O. (Mp-Fe)100 2.61 0,0 ne di i 
Wollastonite, Ca‘ O S251 Desk ne wo 
Hypersthene, (Mg; Be),Onust Osea ee hy 
Olivine;.2 UMg, Pe) Oi Si Oise ee ol 0 
Akermanite, 4:Ca O'S 2° O10e20. 2 yee am 
Magnetite, FeO’. Fey Os. ea: sca een mt 
Femite,“Mg,;e Oi.-5,, S25 aire er aren en mo 
Chromite; Fe Ov,Cre-Os eee cee om H 
Hematite; Pes Os hilo s ices s Seale eee hm M 
Ilmenitte, FeO .°Ti Os:h0 2 se ee eee il Hh 
Apatite, 3-(3 CaO 2 Pi Os SCal laa eee Rd hk Ce ap 
Trotlite,-Pe $.....'s. 6.2 ake shee tr 
Oldhamite, ‘Ca Si5.5°9 2 See eee oh A 
Schreibersite, (Fes Ni)s Pa foe eee se 
Nickel-iron,.Fé,; Nimsco-4- ee cee eee nf 
The methods of calculating the analyses of meteorites in order to 
determine their place in this classification are the same as those adopted 
for terrestrial rocks by the authors of the Quantitative Classification. 
These are given in detail in their publication. As it may be convenient, 
however, to have the quantitative classification of meteorites so far as 
possible complete in itself, so much of the methods of calculation as is 
deemed necessary is here repeated from the work of the authors of the 
Quantitative Classification.* 
1. Determine the molecular proportions of the chemical components of a rock 
as expressed by the complete analysis, by dividing the percentage weights of each 
component by its molecular weight. 
2. Before undertaking the distribution of the chemical components as mineral 
molecules, small amounts of Mn O and Ni O are to be united with Fe O, and of BaO 
and SrO with CaO; of Cre O; with Fe: O3, unless these unusual components occur 
in sufficient amounts to make their calculation as special mineral molecules desirable. 
3. Establish the fixed molecules by allotting: 
a) to Cre Os, if present in notable amount, Fe O to satisfy the ratio Crz O; : Fe O 
; 1 : 1 for chromite: 
b) to Ti Og enough Fe O to satisfy the ratio Ti O2 : Fe O :: 1:1 for ilmenite. If 
there is excess of Ti Os, allot to it equal Ca O for titanite or perofskite according to 
available silica, to be determined later. If there is an excess of Ti Oy it is to be cal- 
culated as rutile. 
* Loc. cit. pp. 188-195. 
