Book V about lodestone, hematite, geodes, hematite, selenite, lapis secularum, asbestos, mica Page 122



	110	DE NATURA FOSSILIUM

	they melt quickly in the furnace they are added to ore from which metals are to be extracted. Glass is made from stones of the third genus, especially when they are found as sand. The sand melts when thrown into the furnace and for that reason the Greeks call it iaXlns άμμος. These stones are sometimes in solid veins, sometimes in more extensive deposits and sometimes found sparingly in metalliferous veins. They are not as hard as silex^il and on that account fire cannot be struck from them. They are not transparent but occur in a variety of colors, for example, white, light yellow, gray, dark blue, black, green blue, reddish brown and red. Although stones of this genus are found in mountainous regions, on the banks of streams and scattered here and there in certain fields, those that are black inside as well as on the surface are rarer.⁴² No matter what the color of the stone they are all criss-crossed with veins of other colors, for example red veins in a white stone. White spots are often found in the green stones, black spots in the gray and reddish-brown spots in the white. Pieces are often found on the surface. They are polished by being rubbed on stones of the same or other genera in stream beds. In this way the pieces are often shaped into spheres that are usually flattened. Light reddish brown stones of this genus are found in the silver mines of Annaberg having the form of a cross, one such stone being four and one-half inches high and three inches wide.⁴³ The vertical portion was three-quarters inch wide, the cross arm one-third inch, both being an inch thick. Material has been found at Freiberg with the silhouette of a monkey as well as other material the size of a red chestnut. The latter material had a whitish upper surface with a small red shield with four lines running around it, the first and third being white, the other two red. A yellowish stone from the Bochantian district of the Carpathian Mountains appears to be eaten. This offers a great variety of uses. The colored stones are spread on the highways. The blue is added to the ashes of the wood of the fir tree and after being burnt is used by dyers. The white is burned, seived and then glass is made from this sand. The whiter the stone the more useful. The Belus river that rises at the foot of Mt.Carmel in Phoenicia between the district of Ptolemais and the city of Tyre carries abundant glass sand to the ocean where the waves wear away all impurities and polish it, according to Pliny. The Volturno river also carries sand to the ocean where, after being reworked by the waves, it is cast on the beach between Cuma and Lucrino. Actually glass is not made from this sand alone. Three parts are mixed with one of nitrum and then, when melted, the material is called ammonitrum. If nitrum is not available ⁴¹ Bermannus, page 467,—"The fourth genua (of rooks) is by far the hardest of all and is named for horn which it resembles in color (German, hornstein). This is called silex by the Latins." ⁴² Flint. ⁴³ Staurolite, possibly.