BOOK V. 115 



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 worth 

 while to dig them. The Indians and some other races do search for gems in 

 veins hidden deep in the earth, but more often they are noticed from their 

 clearness, or rather their brilliancy, when metals are mined. When they 

 outcrop, we follow veins of marble by mining in the same way as is 

 done with rock or building-stones when we come upon them. But 

 gems, properly so called, though they sometimes have veins of their own, 

 are still for the most part found in mines and rock quarries, as the 

 lodestone in iron mines, the emery in silver mines, the lapis judaicus, 

 trochites, and the like in stone quarries where the diggers, at the bidding 

 of the owners, usually collect them from the seams in the rocks. 10 Nor does the 

 miner neglect the digging of " extraordinary earths," 11 whether they are found 



Silex ex eo iclu Jerri 

 facile ignis elicitur. 

 . . . excubus 

 figuris . . . . . . . . Feldspar . . . . *Feldspar 



Medulla saxorum . . Steinmarck . . .. Kaolinite . . . . Porcelain clay 



Fluores (lapides gem- 

 marum simili} .. Flusse .. .. Fluorspar .. 'Fluorspar (see note 



Marmor in metallis 15, p. 380) 



repertum .. . . Spat . . . . Barite . . . . *Heavy spar 



Apart from the above, many other minerals are mentioned in other chapters, and 

 some 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 ; the 

 second 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 require 

 more space than can be afforded. It is mentioned by many Greek writers, including 

 Hippocrates (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 maintained 

 the existence of a stone, theamedes, having repellant properties, and the two were supposed 

 to 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, and 

 Dana (Syst. of Mineralogy, p. 211) considers the stone of Armenia, of Theophrastus (77), to be 

 emery, although it could quite well be any hard stone, such as Novaculite which is found 

 in 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." Many 

 fossils were included among the semi-precious stones by the Ancients. Pliny (xxxvn, 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 so 

 called from a wheel, and is related to lapis judaicus. Nature has indeed given it the shape 

 of a drum (tympanum). The round part is smooth, but on both ends as it were there is a 

 module from which on all sides there extend radii to the outer edge, which corresponds with 

 the 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, 

 fullers earth, potters' clay, clay used for medicinal purposes, etc., etc. 



