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BOOK I
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17
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gealed
juices embrace sulphur, bitumen, realgar, and orpiment. Similarly, due
to. insufficient knowledge and experience, he divides the genus of
saline minerals into three species, namely, halite, alum, and atramentum su-torium. Halite has a saline taste but alum and atramentum sutorium have
only a very faint saline taste. Yet the classes of meager congealed
juices have been distinguished by taste and other qualities.
Albertus
calls minerals which have the properties of both stones and metals by
an intermediate name. He recognizes that metals characteristically
melt in fire while stones do not. For this reason he considers stones
to be dry and earthy, metals moist and aqueous. He regards intermediate
minerals as having the properties of both a dry earth and a liquid.
Certain of these are composed principally of earth, others of water.
The intermediate minerals include halite, nitrum, alum, atramentum sutorium, orpiment, pyrite which is called marchasita by the Moors, pompholyx, and slag which is called σκωρία in
the Greek language. By this classification minerals that have a mixed
composition are called intermediate although actually pyrite is the
only one that is truly intermediate since in this case stone is mixed
and combined with a metal. Halite, nitrum, alum, and atra-mentum sutorium have neither a stone nor metal in their composition although they may be united and joined together with semi-stones. Arsenicum is rarely metallic, never intermediate. Pompholyx, concerning
which Albertus has written, and slag are not natural substances but are
produced in furnaces. Basing our classification on the above arguments,
if we call intermediate only those minerals formed from water and
earth, we will have in the intermediate class stones and metals which
are composed of these elements. Since, however, some stones melt in
fire and some do not, resistance to melting is not a characteristic of
stones for if it is, then stones which melt would not be stones but
intermediate minerals. No one has dared to say this, not even Albertus
himself. Similarly Avicenna is not able to classify earths in any
correct genus. Since I am about to discuss each genus of bodies formed
in the earth, what it is and its nature, I shall regard earths as mixed
minerals and, speaking frankly, disregard the opinions of certain of
the Greeks.
There
are two forms of subterranean bodies without life, one of which,
because it is blown out and flows out from the earth we call by a
characteristic name, the other we call mineral. A mineral body may
form from portions of a similar substance, for example, gold, every
particle of which is gold, or from dissimilar substances such as a clod
which is composed of earth, stone, and metal. Actually it is separable
into earth, stone, and metal. The former mineral body we call
non-composite, the latter, composite. The non-composite bodies we
divide still further into simple and mixed. There are four kinds of
simple mineral bodies, earth, congealed juice, stone, and metal. There
are many kinds of mixed mineral bodies which I shall discuss a little
later.
Earth is a simple mineral body which can be worked in the hands when
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