1868. | The Iron Ores of Great Britain, 35 
morganshire. The Iron ore deposits at Llantrissant, which have 
only of late years attracted marked attention, appear to have been 
worked at least two centuries since. ‘The name of the principal 
mine is Mwyndy, and this is derived from the estate in which the 
mineral is found. The word signifies Ore, therefore Mwyndy House 
is “ Ore House,” and around it in all directions we now find Iron 
slag and remains of the charcoal with which it was once smelted. 
~ This Iron ore, which is now worked by two companies only, “ The 
Mwyndy Iron Ore Company,” and “ The Bute Hematite Company,” 
partakes in its general character of the ordinary conditions of the 
Brown Hematites. Its situation is similar to that of the White- 
haven Red Hematite, and it does not appear in this respect to 
differ from the ferruginous deposits of the Forest of Dean. It 
occurs at, or rather immediately beyond, the southern outcrop of 
the Coal Measures of South Wales. Between the coal seams 
immediately south of the village of Llantrissant and these Iron ore 
deposits, the Permian rocks occur, these being represented more 
especially by large masses of Conglomerate. It will be seen by the 
section given (Fig. 5), that we have conglomerate and shale rocks 
resting on the limestone formation, which here forms the boundary 
of the South Wales coal basin. Under the conglomerate and coal 
measure shale, in which some thin bands of coal occur, the Iron ore 
is deposited on the upturned edges of the limestone, and in the 
fissures formed in that rock. It has been thought hitherto that the 
ore would: be found only at the line of inclination of the limestone, 
but a recent discovery has shown that it suddenly descends into 
the limestone itself. This vertical mass of ore (Fig. 6) may be 
found to terminate abruptly, as shown in the Ulverstone section, or 
it may lead to a limestone cavern which has been filled in with this 
peroxide of iron. In the immediate neighbourhood of this deposit 
a small band of argillaceous nodular iron has been discovered. 
At Frampton Cotterel, in the Bristol Coal-field we find the 
Brown Hematite occurring in the Pennant Grit, or sandstone bed 
of the coal-measures. ‘This iron ore deposit has been formed in a 
great fault, evidently under similar conditions to those which have 
regulated the deposits already named, in the limestone. 
Numerous deposits of Brown Iron ore exist in Cornwall and 
Devonshire. Near St. Austell in the former county, and near Brix- 
ham and Newton Abbot in the latter, these ores are worked with 
success. The Brown Hematites of North Wales and other dis- 
tricts have not as yet attracted much attention. A very remarkable 
ealciferous Brown Hematite occurs at Froghall, near Cheadle, in 
North Staffordshire, which is largely used in the iron works of 
South Staffordshire. This ore, which occurs in the lower coal 
measures, may probably be regarded as an altered highly ferru- 
ginous limestone. 
p 2 
