io8

BOOK V.

rudis ®, of yellowish green, yellow, purple, black, or outside red and insidegold colour. These must be reckoned as the richest ores, because the goldexceeds the stone or earth in weight. Next come all gold ores of which eachone hundred librae contains more than three unciae of gold 7 ; for although buta small proportion of gold is found in the earth or stone, yet it equals in valueother metals of greater weight. 8 All other gold ores are considered poor, because

*Rudis, —“ Crude.” By this expression the author really means ores very rich inany designated metal. In many cases it serves to indicate the minerals of a given metal, asdistinguished from the metal itself. Our system of mineralogy obviously does not afford anacceptable 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.”

7 The reasons for retaining the Latin weights are given in the Appendix on Weightsand Measures. A centumpondium weighs 70.6 lbs. avoirdupois, an uncia 412.2 Troygrains, therefore, this value is equal to 72 ounces 18 pennyweights per short ton.

8 Agricola mentions many minerals in De Re Metallica, but without such descriptionas would make possible a hazard at their identity. From his De Natura Fossilium, however,and from other mineralogies of the 16th Century, some can be fully identified and otherssurmised. While we consider it desirable to set out the probable composition of theseminerals, on account of the space required, the reasons upon which our opinion has been basedcannot be given in detail, as that would require extensive quotations. In a general way, wehave throughout the text studiously evaded the use of modern mineralogical terms—unlessthe term used to-day is of Agricola’s age—and have adopted either old English terms ofpre-chemistry times or more loose terms used by common miners. Obviously modernmineralogic terms imply a precision of knowledge not existing at that period. It must notbe assumed that the following is by any means a complete list of the minerals described byAgricola, but they include most of those referred to in this chapter. His system of min-eralogy we have set out in note 4, p. 1, and it requires no further comment here. Thegrouping given below is simply for convenience and does not follow Agricola’s method. Wherepossible, 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 probablemodern 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 theoriginal. As an indication of Agricola’s position as a mineralogist, we mark with an asteriskthe minerals which were first specifically described by him. We also give some notes onmatters of importance bearing on the nomenclature used in De Re Metallica. Historical noteson 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 goldminerals, green, yellow, purple, black, etc. There is nothing, however, in his works thatpermits of any attempt to identify them, and his classification seems to rest on ganguecolours.

Silver Minerals.

Argentum purum in venisreperitur

Argentum rude ..

Gedigen silberGedigen silber ertz

Argentum

colons

rude plumbei

Argentum rude rubrum

Argentum rude rubrumtranslucidum ..Argentum rude album

Glas ertz

Rot gold ertz

Durchsichtig rodgulden ertz

Weis rod gulden ertz :Dan es ist frisch wieofftmals rod guldenertz pfleget zusein ..

Argentite(Ag 2 S)Pyrargyrite(Ag 3 Sb S 3 )Proustite(Ag 3 As S 3 )

♦Native silverRudis silver, orpure silverminerals

♦Silver glance

♦Red silver

♦Ruby silver

White silver