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56
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DE NATURA FOSSILIUM
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Physicians select armenium that is smooth, blue, non-granular and easily pulverized. However the stone that is known today as armenium is a mixture of caeruleum and chrysocolla and, although it is brought from Armenia and is the blue color of armenium it is not this stone and the color is so pale that it has a very limited use.28
They say, according to Dioscorides, that aerugo forms
in two ways in copper mines, especially the Cyprian mines. It occurs as
an efflorescence in small amounts on copper bearing stones, this being
the best variety, or as drippings in certain caves. The latter mineral
is of poor quality because it is mixed with gravel and other minerals
that make it as hard as stone. This has a deep and pleasing color.
First the mineral is pulverized then collected dry.29
There are three other closely related minerals, one the Greeks call σκώληξ since it resembles worms, another ids ξησός because
it is obtained by scraping. Likewise there are three artificial genera,
one scraped from copper, one with the form of worms and the third made
in copper mortars from the urine of old men. As I have said before, the
latter is called chrysocolla. I will describe how aerugo is made in Book IX. Aerugo has
a pale blue color and an acrid taste. Painters and physicians use all
kinds while goldsmiths use only that which will solder gold to gold. In
medicine Dioscorides preferred the native mineral with a worm-like form
and gave second place to the native mineral obtained by scraping. He
regarded the artificial minerals as of little value for he says that
they bite more than the native minerals. Goldsmiths use that which has
the appearance of scrapings. Aerugo destroys groAvths and although it stings it decreases and dissolves both hard and soft skin ulcers.
Since ferrugo constitutes
an imperfection in metal I will speak of it here. Pure iron, from which
this forms, is rarely found within the earth. Some call this mineral rubigo because it forms as a scale on iron which is in contact with moisture, others call it rubigo because of its color, blackish red. It is described as red by some, black by others. It is just as astringent as atramentum sutorium but
less corrosive. For this reason leather workers dissolve it in stronger
Zittau solution and use it to dye leather. When a linen cloth has been
stained with rubigo it is difficult to wash it clean.30
I shall now take up two other genera of congealed juices, orpiment
28 From this description it is evident that armenium is a variety of chrysocolla probably from the Katara copper mine in Armenia.
29 The modern equivalent of aerugo is copper rust or verdigris. The names aerugo and
verdigris were and are usually used for various green and blue basic
copper acetates. Agricola apparently includes under this name the
native green copper carbonate malachite. In De Ortu et Causis Subterraneorum, Book III, p. 47, Agricola writes, "If a juice, strongly acid, covers material containing copper, eating it away, it produces aerugo." In Interpretatio he gives the German equivalents for aerugo as griinspan oder spanschgriin "because it was first brought to Germany from Spain. Foreigners call it 'green copper'."
30 Here ferrugo and rubigo can both be identified with rust.
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