O'Beilly — On the Occurrence of Idocrase in Co. Monaghan. 449 
guide) ; but there is no name marked for it on the 6 -inch Survey map. 
It appears as an excavation or cutting, having a length of about 
25 yards (in the direction of the lode and hill), about 5 yards broad, 
and about 4 feet mean depth. The beds of Cambrian slate rock which 
are here transformed into an ore of iron and manganese, have a direction 
about IS'.N.E., and dip to the E.S.E. at about 15° to 20°. Further to 
the S.E., in the direction of Eallybay, the strata having much the 
same direction, dip at higher angles of 45° to 60°, and in places appear 
to be nearly vertical. On the S.E. side of the cutting, the highest 
side, occur two thin lodes, separated by an interval of about 2 feet, in 
the more S.E. of which the Idocrase occurs. This lode presents a 
thickness of about 3 inches, and has a direction of 28° E., and a 
dip E.S.E. at about 60°, the direction being seemingly that of the 
ranges figured on Griffith's Map of Ireland, as occupying the greater 
part of the surface of the Co. Cavan. It might consequently be 
inferred that parallel fissures and lodes exist in these ranges, and that 
they may be metalliferous. The containing rock is the ore of iron 
and manganese already referred to, and which has been reported on 
by Mr. W. Adeney, Curator of the Collections of the Hoyal University 
of Ireland, as containing from 33*4 to 42'2 per cent, of ferric oxide, 
and from 5-9 to 7*55 per cent, of manganese peroxide. Ey his kind- 
ness I am enabled to give the complete analysis of a sample of the ore 
as it occurs in the immediate vicinity of the quartz lode in the Qu.irry. 
He describes the sample as follows : — Taken from the S.-W. corner 
of the Quarry, soft, and easily broken up ; purple-brown in colour, 
giving a red streak." This" sample proved the richest in iron, and a 
complete analysis was therefore made of it. 
Soluble Portion. 
, 42-20 
7-55 
Manganese peroxide, . . 
. 6-24 
Cobaltous oxide, .... 
Nickelous oxide, .... 
j 0-03 
0-35 
0-21 
Phosphoric acid, .... 
0-03 
Water expelled at 120° C, 
3-21 
Loss on gentle ignition, 
. 3-21 
Insoluble matter, ignited, . 
. 37 00 
100-29 
