moved
back and forth it cuts the stone. The sand must be soft and fine, not
coarse and hard. The finer sand cuts the stone into thinner pieces
while coarser sand is used for coarser work. The former makes a thinner
cut and cuts away less marble and produces a surface that is easier to
polish. Soft sand produces a smoother surface. The finest and softest
sand came, at one time, from Ethiopia and from a shallow inlet of the
Adriatic which has dried up recently because of the summer sun. Hard
sands come from India, Naxos, and near Keft, Egypt. Coarse sand is
abundant in rivers.
Marble is polished with sand and flint. At one time a sand from Thebes and finely ground pumice was used. Today tofus and
sandstone are used. The flint formerly came from Naxos or Armenia but
today any hard material is used in its place, usually either very hard
marble or rock.
Certain marbles are used in medicine. Lapis arabicus, having
been pulverized and mixed with flax down will stop bleeding when
placed on hemorrhoids. A dentifrice is made from burnt marble. Alabastrites, having
been burnt and mixed with either pitch or resin will soften hard
swellings and when dissolved in wax will relieve pains in the stomach.
When unadulterated it shrinks the gums. Mixed with rock salt it
destroys unpleasant odors of the mouth and teeth.
Pieces
of marble found in gold, silver, and other veins are dense and have a
natural luster equal to that of polished material. This may be white,
gray, dark red, reddish brown and even liver-colored. So much
concerning marbles.
Tofus, called τώρος by
the Greeks, is similar in color and hardness to Parian marble according
to Theophrastus. It is as light as pumice and was much used for
interior walls in large buildings in Egypt. It was also used to connect
one building with another. Since it is so light it added little weight
to the building. It is found in France about a mile from Coburg in the
fields near the Thuringian forest. It is carried by the Elba, a small
river of Thuringia. It is found in the province of Mansfeld where it is
used to build walls and fortifications. The tofus from the Harz
Forest of Stolberg is used to build furnaces. There are quarries on Mt.
Dester, Saxony. All these localities produce white tofus. Whitish
material is found at Pisa, Venice and Umbria, Italy, and was known to
Vitruvius. When notched it can be used to cut wood. Red and black
varieties are found in Campania.
Tofus is
not always hard. It does not melt in a fire, as a rule, nor harden but
falls into a powder instead. Stones which form in caves from juices
that drip from the back and harden, because of the cold, are also
called tofus.10
Sihx is the next mineral to be considered. It is my opinion that the name
10 This term is given primarily to tufa, both siliceous and calcareous, but probably embraces some tuff.
