MINERAL CONSTITUENTS OE METEORITES. 
213 
that of the Manegaum enstatite if we deduct the L5 per cent, of silica that the analysis 
gives in excess. 
The specific gravity of the Manegaum enstatite is 3T98, its hardness is 5-6. 
A small portion of the meteorite was taken for analysis in its entirety. A black 
mineral disseminated in a hand running through it in minute crystalline particles is 
chromite; its formula is assumed as FeCr 2 0 4 . 0-4078 grm. was analysed by the 
hydrogen fluoride method, and gave the following results : — 
Silicic acid .... 
= 0-2187 
per cent. Oxygen ratios. 
53-629 = 28 602 
Magnesia .... 
- 0-0951 
23-32 = 9-3281 
Iron monoxide. . . 
= 0-0835 
20-476 = 4-55 
Iron monoxide . 
CO 
T— < 
o 
o 
o 
II 
. 1-029 
1-495 = 0-427 
► 14-305 
Chromium sesquioxide 
Lime 
= 0-0029 J ' 
= 0-0061 
0-4076 
99-949 
The silicic acid in this sample of the entire meteorite is in the exact proportion requi- 
site for the enstatite formula ; it is therefore not improbable that the excess found in 
the green enstatite may have been due to an error in the analysis rather than to the pre- 
sence of either free silica or of a silicate with a higher proportion of this ingredient. 
The Manegaum meteorite contains a very minute amount of meteoric iron, far too 
small for isolation and analysis ; indeed the portion taken for analysis could hardly have 
contained a trace of it. 
This meteorite is interesting as presenting us with an instance of a meteoric rock con- 
stituted of a single silicate, and that enstatite. It differs from the mass of the Busti 
meteorite in that the latter is a nearly pure magnesian enstatite, while that of Manegaum 
is a highly ferriferous one. The two meteorites concur also in the light they throw on 
the nature of the flocculent opaque white mineral seen in the microscopic sections of 
many meteorites. In these two cases, at least, that mineral is enstatite. 
In concluding this memoir, in which I have endeavoured to deal as exhaustively as 
possible with the constitution and characters of two remarkable meteorites, I wish to record 
the great services rendered me in its investigation by Dr. Flight, Assistant in my De- 
partment at the British Museum, to whose manipulatory skill and care I am greatly 
indebted in the chemical part of the inquiry. 
2 F 
MDCCCLXX. 
