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BOOK V. 



rudis*, of yellowish green, yellow, purple, black, or outside red and inside 

 gold colour. These must be reckoned as the richest ores, because the gold 

 exceeds the stone or earth in weight. Next come all gold ores of which each 

 one hundred librae contains more than three unciae of gold' ; for although but 

 a small proportion of gold is found in the earth or stone, yet it equals in value 

 other metals of greater weight.* All other gold ores are considered poor, because 



'Rudis, — " Crude." By this expression the author really means ores very rich in 

 any designated metal. In many cases it serves to indicate the minerals of a given metal, as 

 distinguished from the metal itself. Our system of mineralogy obviously does not afford an 

 acceptable equivalent. Agricola {De Nat. Foss., p. 360) says : "I find it necessary to call 

 " each genus (of the metallic minerals) by the name of its own metal, and to this I add a 

 " word which differentiates it from the pure (puro) metal, whether the latter has been mined 

 " or smelted ; so I speak of rudis gold, silver, quicksilver, copper, tin, bismuth, lead, or iron. 

 " This is not because I am unaware that Varro called silver rudis which had not yet been 

 " refined and stamped, but because a word which will distinguish the one from the other is 

 " not to be found." 



'The reasons for retaining the Latin weights are given in the Appendix on Weights 

 and Measures. A centumpondium weighs 70.6 lbs. avoirdupois, an uncia 412.2 Troy 

 grains, therefore, this value is equal to 72 ounces 18 pennyweights per short ton. 



^Agricola mentions many minerals in De Re Metallica. but without such description 

 as would make possible a hazard at their identity. From his De Natura Fossilium, however, 

 and from other mineralogies of the l6th Century, some can be fully identified and others 

 surmised. While we consider it desirable to set out the probable composition of these 

 minerals, on account of the space required, the reasons upon which our' opinion has been based 

 cannot be given in detail, as that would require extensive quotations. In a general way, we 

 have throughout the text studiously evaded the use of modern mineralogical terms — unless 

 the term used to-day is of Agricola's age — and have adopted either old English terms of 

 pre-chemistry times or more loose terms used by common miners. Obviously modern 

 mineralogic terms imply a precision of knowledge not existing at that period. It must not 

 be assumed that the following is by any means a complete list of the minerals described by 

 Agricola, but they include most of those referred to in this chapter. His system of min- 

 eralogy v/e have set out in note 4, p. i, and it requires no further comment here. The 

 grouping given below is simply for convenience and does not follow Agricola's method. Where 

 possible, we tabulate in columns the Latin term used in De Re Metallica; the German equiv- 

 alent given by the Author in either the Interpretatio or the Glossary ; our view of the probable 

 modern equivalent based on investigation of his other works and other ancient mineralogies, 

 and lastly the terms we have adopted in the text. The German spelling is that given in the 

 original. As an indication of Agricola's position as a mineralogist, we mark with an asterisk 

 the minerals which were first specifically described by him. We also give some notes on 

 matters of importance bearing on the nomenclature used in De Re Metallica. Historical notes 

 on the chief metals will be found elsewhere, generally with the discussion of smelting methods. 

 We should not omit to express our indebtedness to Dana's great " System of Mineralogy," 

 in the matter of correlation of many old and modern minerals. 



Gold Minerals. Agricola apparently believed that there were various gold 

 minerals, green, yellow, purple, black, etc. There is nothing, however, in his works that 

 permits of any attempt to identify them, and his classification seems to rest on gangue 

 colours. 



Silver Minerals. 

 Argentum purum in venis 



reperitur . . . . Gedigen silber 



Argentum rude . . . . Gedigen silber eriz . . 



Argentum rude plumbei 

 coloris . . 



Argentum rude rubrum . . 



Argentum rude rubrum 



translucidum . . 

 Argentum rude album 



Glas ertz 

 Rot gold ertz 



Durchsichtig rod 

 gulden ertz . . 



Weis rod gulden ertz : 

 Dan es ist frisch wie 

 offtmals rod gulden 

 ertz pfleget zusein . . 



Argentite 



(Ag^S) 

 Pyrargyrite 



(AgsSbSj) 

 Proustite 



(Ag3 As S3 ) 



•Native silver 

 Rudis silver, or 

 pure silver 

 minerals 



*Silver glance 



*Red silver 



♦Ruby silver 



White silver 



