blow of a hammer and contains more silver than the transparent ruby silver which breaks into pieces under the blow of a hammer ,6·7
The white silver mineral (argentum rude album) differs
from native silver in that the latter spreads under the blow of a
hammer as does refined silver. White silver mineral is mined in many
places in Bohemia, especially at Cotteberg. I have seen a little taken
from the upper part of the Divine Gift mine at Abertham. Gray, black,
purple, liver-colored, and yellow natural silver minerals differ from
those already mentioned in color but not in composition.8 They do not have the variety of forms of
β
This was probably a mixture of argentite or native silver and ruby
silver. The dark ruby silver mineral pyrargyrite and the black silver
minerals stephanite and polybasite are brittle.
7 Agricola refers to argentum rude rubrum in Bermannus on page 445 as follows,— Bermannus. "... I shall take up the red genus first.
Naevius. "It appears to be some genus of carbunculus.
Bermannus. "Quite true, but the carbunculus is
usually a brighter red while this is a softer shade. It occurs in
various forms. Sometimes it has a blackish shade, sometimes it is
scattered over rocks like sparks, sometimes solid masses adhere to
rocks. It m.&y occur in simple masses, either with portions
of the mineral projecting upward with pointed ends or the mass may have
the appearance of a vein. When it is quadratic it usually has the form
of a cube. When hexagonal it resembles diamond, and it may even have
more and unequal angles as does the gem iris quartz. Also one can find
this mineral sprinkled with a beautiful blue color that gives it great
beauty and it appears to me that Nature itself, having been exhausted
by such perfect work revived itself with this most beautiful mineral
of all. Perhaps such beauty can be obtained by art but only with the
greatest effort.
Naevius. "This genus of silver was not known to the Ancients?
Bermannus. "Not that I know of unless Theophrastus refers to this mineral in his book De Lapidibus. When
discussing gold and silver minerals found in mines he describes one
with these words, 'another stone has the color of a live coal.'
Ancon. "How much of its mass is lost when it is smelted?
Bermannus.
"Very little as is also true of the lead-colored silver mineral. Hot
dry vapors coming up from the depths of the earth color the essence
from which Nature produces silver and because of variations in this
essence the silver minerals have a variety of colors.
Ancon.
"I believe that you are right in believing that Aristotle would not
have observed this. Has this mineral any other use than as a source of
silver?
Bermannus.
"In paintings. A well known color is made from it, a color that is not
inferior to cinnabar that was so highly prized by the Ancients and
superior to realgar.
Naevius. "Would it be used in medicine by any chance?
Bermannus. "It is probably valueless since no one has experimented with it as yet."
8
It is difficult to ascertain which silver minerals were included under
these various color classes. No doubt there was considerable confusion
in the use of these names in the time of Agricola. The principal silver
minerals in the mines known to Agricola were native silver, argentite,
acanthite, proustite, pyrargyrite, polybasite, stephanite,
tetrahedrite, sternbergite, argentopyrite and cerargyrite. It is
possible that some silver telluride minerals are included here. The
minerals that may have been included in these classes are given below.
