106 The American Geologist. August, isoi 
opened into the fissure, its widest part, five millimetres across, 
and having a varying depth of from five to six millimetres. 
This groove, retaining these dimensions, extended right across the 
face of the specimen, whicli face, in this direction, measured four 
centimetres. There was nothing to indicate what the probable 
length of this groove may have been, as it occurred in the rock, 
in situ, or whether it occupied a vertical, horizontal, or intermedi- 
ate position, although conjecture might perhaps, in this particu- 
lar instance, favour the former view. It was closely packed with 
material of precisely the same character as that contained in the 
fissure, the material of the one forming an uninterrupted connec- 
tion with and. as it were, extension of, that of the other, so that 
we may indifferently regard the material in the fissure as an over- 
flow from the groove, or that in the latter, more especially if this 
merel}' represented an elongated cavit}', as a filling in from the 
former. 
No metallic grains or matter likely to have resulted from the al- 
teration of the same, or mineral from which the iron could possi- 
bh' have been derived, was observable in any other part of the 
specimens examined. 
The material which, as alreadv remarked, had an oolitic struct- 
ure, was dense in texture and firml}' adherent to the face of the 
quartz. It was found to be made up of: 
^Metallic grains 58.85 
Limonite 39.73 
Siliceous matter \A2 
100.00 
The siliceous matter consisted of angular particles of quartz which 
had evidently been chipped off with, and remained attached to the 
material when removing it from the rock. 
The metallic grains varied greatly in size, the largest not ex- 
ceeding thirty-seven hundredths of a millimetre in diameter, 
whilst many, perhaps the greater number, were of far smaller di- 
mensions, and others were of microscopic minuteness. Although 
diverse in form yet all were rounded and, for the most part, more 
or less spherical in shape. The}' were strongly attracted I)}- the 
magnet and after separation by its aid from the associated non- 
metallic matter, aggregated themselves into loose bunchy masses 
or formed trains. Brittle — in the process of pulverization 
emitted a faint yet distinct phosphorretted odour. Colour of 
freshly fractured surface of metal, steel-grey. AVhen immersed 
