1868. ] The Iron Ores of Great Britain. 31 
limits of this article prohibit the further pursuit of the ideas which 
guide modern chemists in their investigations, but we have followed 
these latest developments sufficiently to show that, notwithstanding 
their widely-different aspects, one and the same leading idea under- 
lies the chemistry both of the past and of the present. 
VY. THE IRON ORES OF GREAT BRITAIN. 
By Rozsert Hunt, F.R.S., Keeper of Mining Records. 
In the year 1866 more than ten million tons of Iron ores were 
submitted to the action of fire in 613 blast furnaces, and from them 
we obtained about four millions and a half tons of Pig Iron. The 
great importance of these minerals, regarding them merely as sources 
from which we draw the material for the manufacture of our almost 
infinite variety of machines and tools, our rails, our armour-plates, 
and nearly every description of implement and cutting imstru- 
ment, necessarily renders any examination of the phenomena con- 
nected with their occurrence in Nature of considerable interest. 
We find Iron disseminated through every rock, and in various 
conditions of aggregation in almost every geological formation, 
playing often a very important part in giving character to the 
mass. Indeed, the fact that this metal is found in each of the three 
Kingdoms of Nature indicates some especial function, which is 
not yet clearly appreciated, of equal importance in the organic and 
the morganic worlds. It is, however, only with the occurrence 
of Iron in rock-masses that this paper will deal. It is intended 
especially to examine the peculiar conditions under which some of 
the varieties of Iron ores occur, and to discuss the circumstances 
which probably attended the formation of many of our ferruginous 
deposits, whether occuring as nodular concretions, intercalated with 
our coal-beds, as crystalline mineral forming lodes in the older rocks, 
or as sedimentary beds, spread over wide areas of very different 
geological ages. 
The following list gives the varieties of commercial Iron ores 
produced and used in this country, showing the average percentage 
yield of Iron of each variety, and the proportions in which they 
are employed in the Iron manufactures of these Islands :— 
Per cent. Proportions 
of Iron. in which used. 
Red Hematite ae sr 65°13 15 per cent. 
Magnetic Oxide... ac 56°10 2 aH 
Brown Hematite .. zs 41°40 Ler ee 
Ditto Ditto (Oolitic) .. 35°60 206 es 
Spathose Ores Ee oe 40°95 2 ae 
Black Band .. AP ne 37° 8 49 
Argillaceous Ores .. a eA, 2 
Mean average of all, if used ay 
in equal quantities fe 47°30 100 
