so with the perfect
loadstone which yields the best of iron. There is also a rusty ore of iron,
one of a leaden hue tending to black, one quite black, or black mixed with
true cobalt: there is another sort mixed either with pyrites, or with
sterile plumbago. One kind is also like jet, another like bloodstone. The
emery used by armourers, and by glaziers for glass-cutting, called amongst
the English Emerelstone, by the Germans Smeargel, is ferruginous; albeit
iron is extracted from it with difficulty, yet it attracts the versorium.
It is now and then found in deep iron and silver diggings. Thomas Erastus
says he had heard from a certain learned man of iron ores, of the colour of
iron, but quite soft and fatty, which can be smoothed with the fingers like
butter, out of which excellent iron can be smelted: somewhat the same we
have seen found in England, having the aspect of Spanish soap. Besides the
numberless kinds of stony ores, iron is extracted from clay, from clayey
earth, from ochre, from a rusty matter deposited from chalybeate waters; In
England iron is copiously extracted in furnaces often from sandy and clayey
stones which appear to contain iron not more than sand, marl, or any other
clay soils contain it. Thus in Aristotle's book _De Mirabilibus
Auscultationibus_[74], "There is said" (he states) "to be a peculiar
formation of Chalybean and Misenian iron, for instance the sort collected
from river gravel; some say {23} that after being simply washed it is
smelted in the furnace; others declare that it and the sediment which
subsides after several washings are cast in and purified together by the
fire; with the addition of the stone pyrimachus which is found there in
abundance." Thus do numerous sorts of things contain in their various
substances notably and abundantly this element of iron and earth. However,
there are many stones, and very common ones, found in every soil, also
earths, and various and mixed materials, which do not hold rich substances,
but yet have their own iron elements, and yield them to skilfully-made
fires, yet which are left aside by metallick men because they are less
profitable; while other soils give some show of a ferruginous nature, yet
(being very barren) are hardly ever smelted down into iron; and being
neglected are not generally known. Manufactured irons differ very greatly
amongst themselves. For one kind is tenacious in its nature, and this is
the best; one is of medium quality: an