FOSSILIFEROUS HAEMATITE NODULES IN LEICESTERSHIRE. 67 
Hardman (see “ Geol. Magazine,” Yol. x., p. 395), descriptive 
of some peculiar siliceous nodular brown haematite in the 
Carboniferous rocks in Co. Tyrone, an attempt is made, and 
some chemical formulae are given, to show how by a com¬ 
plicated series of re-actions and so forth, it is perhaps 
theoretically possible to replace the siliceous and clayey 
materials by iron oxides, as he maintains the Tyrone nodules 
have been the result of some such chemical process. That 
rich red haematite has by natural chemical re-actions been 
produced, directly or in situ, from clay-ironstone is, however, 
a fact notwithstanding, as will be shown further on. 
The various kinds of structure noticed would probably 
be due to change of molecular structure, though we 
must admit that one or two of them (stalactitic, columnar, 
and some of the agate forms) are difficult to account for. The 
agate-like markings are occasionally met with in certain 
kinds of dense haematites, and in these instances they 
probably do not represent original structures of the car¬ 
bonates. What most puzzles me is the occurrence of mag¬ 
netite (polarity) and the manner in which the magnetic 
iron exists in the nodules. The presence of some Fe 0 
is probably connected with this peculiar property. The writer 
has not been able to learn that iron ore of this particular 
character has been found or noticed to possess polarity 
before. How and when this property was given them I must 
ask our electrical and philosophical friends to enlighten us 
if they can and will kindly do so. 
I have yet to explain (under this second theory) how 
the intermediate or half-and-half forms of haematite and 
gritty sandstones, &c., were probably formed. And here it 
should be stated that the more closely these associated rock 
fragments are examined the less able are we to draw a line 
between the haematites and them. The same process that 
caused the conversion of the clay ironstones into iron oxide, 
viz., long-continued chemical action, I take it, produced 
these semi-liaematitic specimens. They seem to show that 
the chemical change has not gone quite so far with them, 
quartz probably being less easily acted upon or replaced than 
clay ironstone. 
In order to show that I uphold theory No. 2 in preference 
to theory No. 1, I will state a few additional facts and 
opinions having important bearing upon the questions involved. 
We have been considering these nodules, &c., as pseudo- 
morphous. During what geological period or periods the 
transformation took place I will now proceed to discuss. 
The fact of the stones being now obtained, or being derived 
