Vol. VIIT, No. 9.] The Origin of Meteorites. 317 
[NV.8.] 
cularly dense form of the graphite occurring in rocks nearer the 
surface. 
Normally, the infra-plutonic rocks will not reach the earth’s 
surface, as their upward passage must in most cases be accom- 
panied by a reduction of pressure whilst the temperature is 
II.—Or1ciIn or Merrorires. 
With this short introduction we may turn to the brief 
€Bisniivias consideration of meteorites. Whilst I was 
Cotter brought me for opinion two thin slices of meteorites 
that he was engaged in describing. One of them (Baroti) 
represented a non-chondritic meteorite and the other (Khohar) 
a chondritic one.!_ The moment I glanced through the micro- 
scope at the chondritic meteorite I saw what the chondrules 
-Mhust once have been, namely garnets. The chondrule I was 
statite, surrounded by a rim of metallic iron (see plate XXVIT, 
fig. 1). The conversion of garnet to enstatite is easily explained 
by the following equation :-— 
3 (Mg,Fe)0.Fe,0,.38i0, = 3 (Mg,Fe)SiO. + Fe,0,, 
Garnet Enstatite 
which requires an 8-5 °% increase in volume. The ferric oxide, 
expelled by the crystallising enstatite, was reduced by graphite 

1 An account of these two falls, and of somo other Indian falls, will 
appear in part 4, Vol. XLII, Records of the Geological Survey of India. 
