THE CAROLINE STONY METEORITE 
45 
schreibersite, merrillite and possibly apatite are the only 
likely compounds of phosphorus in the unaltered meteorite 
and since merrillite is relatively unaltered, it seems likely 
that such phosphate as is associated with limonite has been 
derived from phosphide in the nickel-iron. There is thus 
an indirect suggestion that the residual nickel-iron contains 
phosphorus in sufficient amount for the presence of the 
phosphorus-rich constituent schreibersite. 
Pyrrhotite. Pyrrhotite appears in the section as small 
irregular brownish-cream grains of variable size; they are 
magnetic, strongly anisotropic, and resistant to nitric acid, 
but tarnish slowly with caustic potash. In appearance and 
behaviour they are identical with pyrrhotite from other 
sources. Short’s statement (2) that troilite, the iron sulphide 
in meteorites, is attacked by nitric acid with etfervescence, 
was confirmed by a test on troilite in a polished surface of 
the Henbury meteoritic iron. Troilite occurs in iron meteo- 
rites in a matrix of metallic iron, and has frequently been 
reported in stony meteorites. Allen, Crenshaw, Johnston 
and Larsen (3) pointed out that troilite is the end member 
of a series of solid solutions of iron and sulphur known as 
pyrrhotite, and that stony meteorites probably contain 
ordinary pyrrhotite. Examination in reflected light deter- 
mines that the sulphide in the Caroline meteorite is indis- 
tinguishable from pyrrhotite. 
Numerous small particles of pyrrhotite occupy about 3 
per cent, of the area of the polished surfaces, and are gener- 
ally isolated in the silicates from the scarcer particles 
of nickel-iron. In a few instances pyrrhotite is in partial 
contact with nickel-iron or limonite derived from nickel-iron 
(Fig. 1). In rare cases minute particles of pyrrhotite are 
enclosed in nickel-iron. 
Pyrrhotite, though much less weathered than nickel- 
iron, presents all stages of decomposition into limonite; 
decomposition proceeds, not so much from the external surface 
as along fractures, where veins of limonite develop ; all stages 
of alteration are represented, from a pyrrhotite grain trans- 
versed by a network of limonite veins, to a limonite mesh 
containing minute particles of pyrrhotite. Traces of this 
meshwork remain after oxidation is complete and distinguish 
an area of limonite derived from pyrrhotite from one derived 
from nickel-iron. 
Chromite. Grains of chromite are much fewer than those 
of pyrrhotite. One of the larger grains measures 0 18 x 
0 10 mm. Occasional minute particles not more than 0 006 
