302 LIAS Or ENGLAND AND WALES : 
1 2 feet, for the quality of the beds is very variable, the bottom- 
layers of a grey or greenish colour being comparatively poor. 
About 2,000 tons of ironstone were raised in 1859, and the amount increased 
in 1874 to 360,352 tons; of late years the published statistics are merged 
with those of other Lincolnshire iron-works. (See Table, p. 306.)* 
The richer ore contains nearly 40 per cent, of metallic iron, 
and the poorer shelly bands about 12 per cent. The first furnace 
at Frodingham was erected in 1864.t 
The following notes on the Frodingham ironstone .were written 
by Mr. J. J. H. Teall, who examined the rock microscopically 
and chemically : 
" The ironstone consists of oolitic grains of ferric oxide showing 
concentric structure ; and of grains, which appear to be 
pseudomorphs in ferric oxide, of rolled organic fragments. These 
occur in a matrix of calcite. 
" The replacement by iron-compounds (? carbonate) appears to 
have taken place before cementation. If not, why was not the 
matrix also affected as it was in the case of the Cleveland ore ? 
" The residue comprises siliceous balls, quartz, aiid flakes of white 
mica." 
In reference to these notes, it may be interesting to quote the 
remarks of Mr. Allan B. Dick, on the Cleveland Ore. He says 
" Throughout the ore are diffused irregularly a multitude of small 
oolitic concretions, together with pieces of an earthy substance 
resembling the ore but lighter in colour. When a mass of this 
ore is digested in hydrochloric acid till all carbonates and soluble 
silicates are dissolved, there remains a residue having the form of 
the original mass of ore. It is extremeiy light, and falls to powder 
unless very carefully handled. It contains the oolitic concretions, 
or else skeletons of them, which dissolve completely in dilute 
caustic potash, showing them to be silica in a soluble stale. 
Under the microscope some of them are seen to have a central 
nucleus of dark colour and irregular shape, but none of them 
present any indication of organic structure or radiated crystalliza- 
tion.":}: 
Ironstone-nodules occur in the top beds of the Lower Lias, 
and in the lower beds of the Middle Lias, more especially in 
Gloucestershire. 
The Kev. P. B. Brodie mentions that ironstone was formerly 
worked at Robin's Wood Hill, near Gloucester. It seems that the 
forging of iron was once carried on here to a considerable extent. 
The ore was dug out of the hill, and the works were probably 
continued as long as a sufficient supply of wood could be found 
in the neighbourhood. || 
* J. D. Kendall, Trans. N. of Eng. Inst. of Mining Engineers, vol. xxxv. p. 22. 
fUssher, Geol. X. Lincolnshire, p. 22. 
J Iron Ores of Great Britain, Part I., p. 95. 
Quart. Journ. Geol. Soc., vol. ix. p. 31. 
|| G. A. Williams, New Guide to Cheltenham, p. 137. 
