4 FOSSILIFEROUS HEMATITE NODULES IN LEICESTERSHIR . 
common, though now and then a nodule consists merely of a 
thin shell or crust of haematite. For a typical set of these 
stones see Plate I., Figs. 1, 2, 3, 4, 5, 6, 7, 8, 12, and 13. 
In size they vary, as already stated, from mere grains or 
minute bright shot-like morsels of about -^o °f an iud 1 m 
diameter to masses weighing some two to three pounds (the 
weight of the largest I have yet discovered or heard of). I 
possess the greater part of a nodule which when whole 
probably weighed about 56oz. The average of all specimens 
would probably be from lin. to l^in. across, or, in weight, 
about 2Joz. The prevailing colour of the weathered 
fragments is a reddish brown ; iron black and grey are not 
common, but various tints of red, chocolate, purple, yellow, 
&c., are frequently noticed. Occasionally they possess a very 
bright red coating. A few are variegated. Very rarely they 
seem to be composed entirely of yellow ochre (pure limonite). 
Those occurring in situ in the breccia are mostly either of a 
red, or yellow and red, and have a metallic or steel grey 
appearance. Freshly fractured samples exhibit various reds, 
purples, browns, blue-blacks, and greys. Sometimes a white 
softisli substance is found in them occupying hollows and 
cracks, which I conclude to be either sulphate of baryta or 
hydrous silicate of alumina. In the limonite (or gothite) 
nodules, streaks or veins of manganite sometimes are present. 
(b) Structure .—Some seem to exhibit no structure—to 
occur massive. We have bedded, granular, concretionary, 
cellular, mammillated, stalactitic, geodic, columnar, cone-in¬ 
cone, banded, porphyritic, scoriaceous (?), compact, coarse¬ 
grained, fine-grained, brecciated, &c., specimens. In some 
samples we find two or three of these forms in a greater or 
less degree united. The botryoidal or mammillated forms 
occur in specimens of ore usually resembling vein iron-ore. 
Micaceous samples are usually earthy, and are often used as 
“raddle” or “red-rud” in the district. The sp. gr. of the 
most compact ore, i.e., the steel grey variety, = 4*62. 
Hardness .—Say 6^ to 7 for the most compact variety. 
This characteristic is perhaps the chief point or peculiarity 
possessed by the nodules, and it is this that qualifies 
them for employment as “ burnishers.” When thus used, 
excessive liarduess must be accompanied by absence of 
cracks or flaws of any kind. It is, however, only a small 
proportion of the pebbles or fragments of ore that are found 
to be commercially valuable. 
Fracture and Lustre. — Beautifully perfect conclioidal 
fracture in the hardest and faultless specimens, to irregular, 
flinty, dull and earthy. The lustre is metallic adamantine 
(rarely), more often greasy, dull and earthy. 
