BOOK V.

ii5

As regards other kinds of metal, although some rich ores are found,still, unless the veins contain a large quantity of ore, it is very rarely worthwhile to dig them. The Indians and some other races do search for gems inveins hidden deep in the earth, but more often they are noticed from theirclearness, or rather their brilliancy, when metals are mined. When theyoutcrop, we follow veins of marble by mining in the same way as isdone with rock or building-stones when we come upon them. Butgems, properly so called, though they sometimes have veins of their own,are still for the most part found in mines and rock quarries, as thelodestone in iron mines, the emery in silver mines, the lapis judaicus,trochites, and the like in stone quarries where the diggers, at the biddingof the owners, usually collect them from the seams in the rocks . 10 Nor does theminer neglect the digging of “ extraordinary earths ," 11 whether they are found

Silex ex eo ictu ferrifacile ignis elicitur.

• . . excubus

figuris

Feldspar ..

♦Feldspar

Medulla saxorum

Steinmarck..

Kaolinite..

Porcelain clay

Fluores (lapides gem-marum simili)

Flusse

Fluorspar

♦Fluorspar (see note

M armor in metallisrepertum ..

Spat

Barite

15 , P- 380)

♦Heavy spar

Apart from the above, many other minerals are mentioned in other chapters, andsome information is given with regard to them in the footnotes.

10 As stated in note on p. 2, Agricola divided “ stones so called ” into four kinds ;the first, common stones in which he included lodestone and jasper or bloodstone; thesecond embraced gems; the third were decorative stones, such as marble, porphyry, etc.;the fourth were rocks, such as sandstone and limestone.

Lodestone. ( Magnes; Interpretatio gives Siegelstein oder magnet ). The lode-stone was well-known to the Ancients under various names— magnes, magnetis, heraclion,and sideritis. A review of the ancient opinions as to its miraculous properties would requiremore space than can be afforded. It is mentioned by many Greek writers, includingHippocrates (460-372 B.c.) and Aristotle ; while Theophrastus (53), Dioscorides (v, 105),and Pliny (xxxiv, 42, xxxvi 25) describe it at length. The Ancients also maintainedthe existence of a stone, theamedes, having repellant properties, and the two were supposedto exist at times in the same stone.

Emery. (Smiris-, Interpretatio gives smirgel). Agricola (De Natura Fossilium., p.265) says: “ The ring-makers polish and clean their hard gems with smiris. The glaziers‘ use it to cut their glass into sheets. It is found in the silver mines of Annaberg in Meissen‘ and elsewhere.” Stones used for polishing gems are noted by the ancient authors, andDana (Syst. of Mineralogy, p. 211) considers the stone of Armenia, of Theophrastus (77), to beemery, although it could quite well be any hard stone, such as Novaculite—which is foundin Armenia. Dioscorides (v, 166) describes a stone with which the engravers polish gems.

Lapis Judaicus. ( Interpretatio gives Jiiden stein). This was undoubtedly a fossil,possibly a pentremites. Agricola {De Natura Fosilium, p. 256) says : “ It is shaped like an‘‘ acorn, from the obtuse end to the point proceed raised lines, all equidistant, etc.” Manyfossils were included among the semi-precious stones by the Ancients. Pliny (xxxvii, 55,66, 73) describes many such stones, among them the balanites, phoenicitis and the pyren,which resemble the above.

Trochitis. (Interpretatio gives spangen oder rederstein). This was also a fossil,probably crinoid stems. Agricola (De Natura Fosilium, p. 256) describes it: “ Trochites is solt called from a wheel, and is related to lapis judaicus. Nature has indeed given it the shape„ °f a drum (tympanum). The round part is smooth, but on both ends as it were there is a1( module from which on all sides there extend radii to the outer edge, which corresponds with„ fhe radii. These radii are so much raised that it is fluted. The size of these trochites,, varies greatly, for the smallest is so little that the largest is ten times as big, and the largest„ are a digit in length by a third of a digit in thickness . . . when immersed in vinegar

they make bubbles.”

u The “ extraordinary earths ” of Agricola were such substances as ochres, tripoli,tullers earth, potters’ clay, clay used for medicinal purposes, etc., etc.