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DE NATURA FOSSILIUM
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soft
as that from Zuicca, Misena, some medium hard as that from Pirna, while
some is hard as that from Norinberg across the Danube. The latter
material is soft when it is first broken in the quarry and therefore is
worked at once since it becomes quite hard after standing in the air
for some time. The rock from Zuicca will not withstand rain or cold
weather. Cliffs of this rock in France between Colebach and Cuperberg,
when exposed to the air, gradually disintegrate to sand. One variety
from Pirna is composed of a very fine sand and has a smooth surface
when sculptured. The rock from Rochlitz is so coarse that it cannot be
given a smooth surface. Some rock is similar in appearance to fish roe
such as that found between Eisleben and Seberg and within the
sovereignty of Bruno at Noteberg. This resembles salmon roe which is
about the size of rape seed. Another variety found between Eisleben and
Seberg is composed of sand the size of coriander seed, blackish red in
color and covered with a sweetish efflorescence.
Rock
usually occurs in large masses and in quarries large angular blocks can
be obtained. More rarely it occurs in thinner beds as near Bodeberder
and Embach, Saxony. Rock from these thin beds is spread on roads in
many places and is used in both private and public buildings. At both
Embach and Bodeberder they spread it on the roofs of houses. The
rectangular masses are used to build shrines and temples and
especially for columns, windows and door posts. Material which will
harden in air is preferred, for example that from Norinberg mentioned
above. The well known wall of the fortified city of Dresden is built of
this stone and the road to the famous bridge of the Elbe passes through
an arch of this wall. A portion of the fortress of Berlin is built of
the same rock. It is carried to distant and foreign countries via the
Elbe river.
They make millstones from harder and denser rocks and for that reason the Greeks call them μυλίας or μυλίτψ, and the Latins, following the Greeks call them lapis molaris. Such
rocks are found in Saxony near the town of Munda; in Misena near the
fortress of Loma some three miles from Pirna. The millstones are
transported from the former locality via the Weser river and from the
latter via the Elbe. Another type of millstone is found in places that
are burning. This rock forms from molten stone and was called lutum by
Strabo and since it contains an admixed portion of a burning substance
it has a moderate unctuousness. When these burning places erupt they
throw out this molten stone and rivers of it flow away as can be seen
at Etna. This soon congeals in the cold air and is changed into rock
which can be quarried just as any other rock, although Pliny writes
that this is a stone, not a rock. It is only found in those places that
were burning at one time or are burning today. Even when the molten
material is not thrown out it is congealed by the cold of the earth and
changed into rock. Such a material is quarried in Italy near Lake
Vulsiniis and in the district of Statonius; on the island of Nisida;
and on Cape Melaena, Ionia. We do not know if the rock found in
Mesopotamia near the Euphrates belonged to this genus or some other.
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