FOSSILIFEROUS HEMATITE NODULES IN LEICESTERSHIRE. 7 
the oscillations or earth-movements possibly continued 
through long periods of geological time, which the position of 
the Permian series proves to have taken place. But we must 
pass on and next notice some 
Agates. —Under division 2 (b) Concretionary structure was 
noticed. This is very common. Certain very hard and 
flawless specimens of the ore are, by people in the district 
who trade in them as burnishers, termed “agates,” although 
they may display no visible concretionary markings such as 
agates proper possess. The term, I fancy, has been applied 
to signify excessive hardness, and adaptability to uses in 
burnishing, to which the ordinary Scottish, Gferman, and 
other agates are often put. My reason for calling certain of 
my specimens “ agates ” is this. Their structure , I maintain, 
in a great measure resembles that of the true agate. It is 
true we do not in these haematitic forms meet with any 
transparent or semi-pellucid and variegated kinds, but 
generally speaking with only two shades of the same colour, 
and with alternating bands or zones of different density of 
two kinds; in other words, I have only noticed the parallel 
or concentric layers to be composed of two shades of red, 
purple, or blue, as the case may be, however many times 
repeated. Figs. 1, 3, and 4 illustrate forms possessing 
agate-like structure. It often happens that good agate-like 
markings or layers occur in some of the most brittle and 
worthless specimens. These concretionary markings are 
occasionally very beautifully and minutely developed ; the 
forms known as “ fortification,” “ eyed,” “ folded,” and 
“ banded,” being present. Some of these forms probably 
owe their origin to minute cracks in the stone which have 
in some way regulated the development of the peculiar 
structure seen. Again, we occasionally find specimens 
(weathered stones) which at first sight look like the remains 
of nodules, but as a large portion of each of them is com¬ 
posed of a mass of quartz grains cemented together (with 
red haematite inside and brown haematite outside the nodule) 
I am inclined to look upon them as having once been 
fragments of grit or of quartz rock. The most peculiar feature 
about them, however, seems to me that the parallel or 
concentric zones of oxidation not only run through the ore 
devoid of visible quartz grains, but through the gritty part 
of the stone as well. The pittings, cup-shaped or conical 
hollows with “ pin-holes ” in the'bottoms of them, the wart¬ 
like and eyed excrescences, and other surface markings on 
the stones are generally traceable to this kind of con- 
