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Book VII marbles, gems in rings and other applications

Book VII marbles, gems in rings and other applications Page of 251 Book VII marbles, gems in rings and other applications Text size:minus plus Restore normal size   Mail page  Print this page
162
DE NATURA FOSSILIUM
where it is fashioned into cooking vessels which are then bound with iron hoops. The hard rocks should be dressed with iron tools as soon as they are taken from the quarries since they become much harder after stand­ing in the air. These are used in making mortars in which druggists com­pound medicaments and whetstones on which other stones are ground. For these purposes they use the beds of rocks found in Misena between Penica and the fortified city of Roseburg, as well as lapis thebaicus with yellow spots, chrysites from Chalazius, and basanites. The Ancients made mortars from these rocks and also from hard marbles, for example, the greenish marble from Ethiopia, from haematites, from each of the marbles of Taenarius, from Parian marble, Egyptian alabastrites, and from white ophites. Today they make the small mortars used in grinding and pulver­izing emery and other hard stones from our jasper and onyx. Remedies for the eyes are ground and mixed in mortars made from Ethiopian marble since this stone itself, when pulverized on a flint, will destroy the mists that form in front of the eyes.
There are two other genera of rocks but square blocks are not cut from them. One is called "fissile," the other "calcareous." The strata of "fissile" rocks (slate) differ from those of other rocks in that they can be split with ease. They differ in color since the former may be white, yellow, red or some other color while the latter are either gray, whitish gray, light or dark bluish gray, dark blue or black. "Fissile" rock is found in many places but the very best with a dark color, distinctly tabular form, and with golden veins comes to Lipsia from Norinberg. "Fissile" rock will usually split in a fire and the thin pieces produced in this way are used in Germany to cover churches and large buildings.
"Calcareous" rocks are so-called because lime may be produced from them when burnt in a furnace. This genus varies in color. Some is white and the whitest is found in the vicinity of the village of Bruno, especially in the fields of Lichtenberg and even under the walled city of Wolfenbuttel. Some is light gray or gray such as that about two miles from Chemnitz on the road to Waldenburg. Some is dark blue as that from the lime quarry of the village of Averswald five miles from Chemnitz. In the mountains near Sala it is found white, light yellow and light red. A rock that is part white and part light gray is found near the Moecheta river not far from Pirna. The river is used to transport the rock to the country along its course.
The "calcareous" rocks are divided into hard and soft varieties. The rock from near Bruno is soft and easy to work while that from Chemnitz is hard. The Hanover variety is similar to Pirnian marble and when struck gives a resonant sound similar to that of black copper chalcophones. One of these stones in the walled city of Alcathea, Megara, gives a tone similar to the cithara when struck with a pebble but this is obviously due to the artificial carving. Although "calcareous" rock is commonly dense the rock from Sala is loose-textured and full of small holes. It has a variable unc-
Book VII marbles, gems in rings and other applications Page of 251 Book VII marbles, gems in rings and other applications
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