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DE NATURA FOSSILIUM
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Diamond
differs from quartz in hardness. The former is actually so hard that if
placed on an anvil and struck with an iron hammer, the hammer and anvil
will break before the diamond can be fractured or crushed.10
It will not only withstand the blows of a hammer but also fire. If we
are to believe Pliny it will not melt or even glow in the hottest fire.
According to Xenocrates it is not fouled in a fire but is purified.
Nevertheless the exceptional hardness of this remarkable stone can be
reduced by placing it in the blood of a male goat or lion, after which
it can be broken. When placed in liquid lead in a very hot furnace it
will melt. Actually all diamonds are not of the same hardness. Those
from Cyprus and the variety siderites are broken by the blow of
a hammer and holes can be drilled through them with other diamonds.
Pliny writes that he was the first to call these stones "degenerate."
The very finest diamonds can destroy the force of lodestone just as the
blood of a male goat or lion can reduce the hardness of a diamond. When
the diamond is placed next to the iron the lodestone cannot attract it,
or if eventually it does attract the iron it is drawn away violently
from the diamond. A diamond can detect poison and render it harmless.
For this reason it has always been highly prized by royalty and
therefore has always commanded a high price. It is reported to prevent
insanity but this is hard to believe. Finally, gem engravers set broken
fragments of diamond in iron and because of the superior hardness use
them to engrave all other gems.
Androdamas also
forms from a colorless essence. The name, as many believe, comes from
its power to subdue the violence of men and to cool anger (ανδρός, man, δάμασν, subduing).
It is found in Arabia. With the color and luster of silver it has the
appearance of a diamond although it has a different form. It occurs as
a cube. Although it may be cubical and without the same properties
nevertheless it is today called diamond, a hexagonal mineral.
The
following gems are white and multicolored, that is, they change color
when inclined just as does a variety of silk cloth when viewed from
different directions. The Greeks call these gems paederos, the name being derived from the passionate love of youth, because of its exceptional charm (παιδίον, boy; epos, love). In this group of gems the finest is the opalus. When it is inclined one sees in it the weaker fire of the carbunculus, the gleaming purple of the amethyst, the sea green of the smaragdus, and
all of these colors sparkling in an incredible intermixture. Masses are
found the size of a hazelnut. It is found only in India and is more
valuable than the smaragdus. It is brought to us only rarely. The gem that takes second place is called sangenis by the Indians, Semites by
the Egyptians. When inclined this shows the colors copper-red, purple,
and wine-yellow. The wine-yellow color always occurs around the outer
edge while the purple, according to Pliny, spreads to the yellow and
mixes with all the other colors. This gem, pleasing and delightful to
the eye, occurs in India,
10 A fallacy widely held in ancient and medieval times.
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