48 
CLAY IRON ORES. 
coaly matter, occurring as a thin I 
band interstratified in the Coal j 
Measures. Contains sufficient car¬ 
bonaceous matter to calcine itself, 
and thus produces, at little expense, 
from a poor stone a rich iron ore. 
429 to 431. Black-band. 
Upper and lower divisions of the j 
bed at Cambrian Woidis, South \ 
Wales. 
Presented by Dr. Bo^rring. 
432 to 434. Black-band. 
From the Coal Measures at Cwm 
Fhondda fach, Glamorganshire. 
Presented by Captain Basset Saun- 
derson. 
435. Black-band (top stone, 12 
inches thick). 
Beaufort Iron Woi'hs, near Ponty- 
pool, 3Ionmouthshire. 
Presented by C. Barley. 
436. Black-band (middle stone, 
30 inches thick). 
Beaufort Iron Works. 
437. Black-band (bottom stone, 
4 inches thick). 
Beaufort Iron Works. 
Shelf V. 
ARGILLxiCEOUS, 01’ Cl AY-IRON¬ 
STONE, {impure earthy carbonate 
of iron') occurring in concretionary 
nodules and thin beds or bands, 
chiefly in the Coal Measures. 
438 & 439. Argillaceous Iron¬ 
stone. 
Occurring in nodides in the Devonian 
Slates, Exmoor, Devonshire. 
Presented by W. W. Smyth, P.R.S. 
Clay Ironstones of the Coal Measures. 
There are few parts of our British coal-fields vrhich do not contain 
this variety of iron ore. Spread out in sheets of from an inch to 
three or four inches thick, with shales or “ binds ” above and below, or 
dispersed in nodules or “ balls ” even more variable as to size, and 
imbedded in shales or indurated clays, they form the great staple ma¬ 
terial of our iron trade. In each locality the particular beds, very' 
numerous as they sometimes are, are known by special names ; and 
with the name certain characters will sometimes be found to remain 
persistent over an area of miles in extent. But, comparing different 
tracts, these ores are subject to great variations, and the chief wealth 
of the measures may lie in the lower part in one district, in the upper 
part in another. Their value will depend locally on the number and 
thickness of the successive bands within a given height of shaly strata, 
upon the kind of material with which they are associated, and upon the 
comparative richness or poverty, leanness, in iron, of the individual 
beds. 
The average varieties of this ore employed in smelting, contain from 
25 to 35 per cent, of metallic iron. The metal exists in them in the 
form of a carbonate of protoxide, mingled with numerous other sub¬ 
stances, among which ma.y be specifled silica, magnesia, lime, manganese, 
phosphoric acid, and organic matter. 
The clay iron ores are arranged in the cases geographically, begin¬ 
ning with the coal-field of South Wales, and thence passing from the 
south-west to the north-east. From each special district or mine they 
are placed as nearly as possible in the order in which they occur in 
nature. Fuller particulars than can properly be given in a catalogue, 
will be found in the “ Iron Ores of Great Britain,” and in the Sections 
of the Geological Survey. 
