418 J. L. Smnvith—Concretions in Meteoric Irons. 
A fifth concretion I discovered in 1876 in the Cohahuila 
masses, called the Butcher meteorites. It is second to none in 
twelve inches square, which is now in the hands of Professors 
DesCloizeaux and Daubrée for inspection, and for the present 
n t is chromite. The 
. 
in the cabinet of the Garden o 
detailed mineralogical description of them, for they are well 
known by their dark bronze color, which color in troilite of 
the pure type extends unaltered to the very boundary of the 
enclosing iron. They are either granular in structure, or more 
solid with a marked cleavage in one direction; the latter kind 
I have found to be the purest form. It is readily acted on by 
dilute chlorhydric acid, especially when slightly warmed, and is 
was for some time considered identical with the magnetic sul- 
phuret of iron (pyrrhotite); but my labors in 1853* proved Ne 
to be a protosulphuret of iron (FeS); and further examinations 
with the purest specimens have confirmed the first results. 
Rammelsberg and others have, by independent analyses, sus- 
tained this Sospumbenlien. Troilite is hence a meteoric min- 
eral having no terrestrial representative. att 
The iron immediately enclosing these nodules, and within & 
milligram or two of them, gives but a trace of sulphur on 
analysis. The finest type of pure troilite I found is 1n the 
Sevier County iron, although this iron contains nodules of it 
largely mixed with other minerals, 
‘Sate (Phosphuret of iron and nickel (Ni,Fe,P)—We 
do not have to go far in the examination of troilite saben 
before finding some of them coated or penetrated by a bright 
* This Journal, vol. xix. 
