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120
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DE NATURA FOSSILIUM
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the
two in Nero's possession, but even wine ladles such as the one Pliny
mentions which was purchased for eight hundred and fifty pieces of gold
from a none too wealthy woman Η---------s, as well as the faceted spheres
with
which we calculate prices. It is also cut into the faceted hemispheres
from which they make the clusters that are set in rings. Quartz can be
used for relief engraving, especially for coats of arms although it is
rarely employed for this purpose since it wears rapidly \vith use being
softer than a file. It is also used for the lenses that were employed
by physicians in times gone by to burn people when held in the sun's
rays. These lenses produce a dazzling white point of light that can
shatter quartz itself and set fire to material. Hephaestites is
also used for these lenses. Quartz itself is cold and dry. When an
object is placed before it, it will illuminate the portion nearest it
with its brilliancy. The more transparent and brilliant the quartz the
greater its heating power.
Quartz is used in medicine. Having been ground very fine and taken in sour wine it stops dysentery since it is so drying.
The
finest quartz is free from all flaws, transparent and heavy. This
variety is found in the Alps near Sion and the finest crystals of
Germany come from Gombezanus. All other quartz is of inferior quality.
Actually writers judge the beauty of quartz according to its place of
origin. Pliny writes that the finest comes from India and praises the
groups of crystals found in the Alps. He writes that the very poorest
comes from Asia near Alabanda and Orthosia. Solinus writes that the
Scythian crystals are the most valuable. When the rays of the sun
coming through an open door, window or crack are allowed to fall on a
crystal of Scythian quartz it will reflect the rays on a nearby wall
with all the colors of the rainbow and for that reason it is called iris. This
can only be done with colorless, transparent, natural hexagonal
crystals. Indeed it is because of its angles that it can take the rays
of the sun and reflect them on a wall as a rainbow. The crystal that
will produce the largest rainbow with the brightest colors is regarded
as the best. If any one of the angles of the crystal is turned toward
the light and observed carefully a rainbow can be seen within the
crystal. Iris is found in the localities mentioned above along
with other quartz but it is especially abundant along the Weser river
near the town of Hoxer; in Westphalia near Erz on the estate called
Hil-deschespred; in Hesse near Halleberg; and in the mountains between
Trier and the Rhine. Pliny writes that it is dug up on an island in the
Red Sea forty miles from the town of Berenice.
There is another variety of iris that
is not as colorless as quartz and when turned toward the light has a
color as yellow as citron. For this reason gem dealers call it citrina.s Older
writers have described this variety as resembling wax. Since it is not
as transparent as quartz it is not as brilliant and the colors of the
rainbow it throws on the wall of a room are
8 This is the first use of the name citrine for yellow quartz. The name citrina should not be confused with citrinus a variety of chrysolithos.
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