BOOK III. 



REVIOUSLY I have given much information 

 concerning the miners, also I have discussed the 

 choice of locahties for mining, for washing sands, 

 and for evaporating waters ; further, I described 

 the method of searching for veins. With such 

 matters I was occupied in the second book ; now I 

 come to the third book, which is about veins and 

 stringers, and the seams in the rocks^. The 

 term "vein" is sometimes used to indicate canales 

 in the earth, but very often elsewhere by this name I have described that 

 which may be put in vessels^ ; I now attach a second significance to 

 these words, for by them I mean to designate any mineral substances which 

 the earth keeps hidden within her own deep receptacles. 



^Modern nomenclature in the description of ore-deposits is so impregnated with modern 

 views of their origin, that we have considered it desirable in many instances to adopt the 

 Latin terms used by the author, for we believe this method will allow the reader greater 

 freedom of judgment as to the author's views. The Latin names retained are usually 

 expressive even to the non-Latin student. In a general way, a vena profunda is a fissure vein, 

 a vena dilatata is a bedded deposit, and a vena cuniulata an impregnation, or a replacement 

 or a stockwerk. The canales, as will appear from the following footnote, were ore channels. 

 " The seams of the rocks " (commissurae saxorum) are very puzzling. The author states, as 

 appears in the following note, that they are of two kinds, — contemporaneous with the formation 

 of the rocks, and also of the nature of veinlets. However, as to their supposed relation to 

 the strike of veins, we can offer no explanation. There are passages in this chapter where 

 if the word "ore-shoot" were introduced for "seams in the rocks" the text would be in- 

 telligible. That is, it is possible to conceive the view that the determination of whether an 

 east-west vein ran east or ran west was dependent on the dip of the ore-shoot along the 

 strike. This view, however, is utterly impossible to reconcile with the description and 

 illustration of commissurae saxorum given on page 54, where they are defined as the finest 

 stringers. The following passage from the Nuizliche Bergbilchlin (see Appendix), 

 reads very much as though the dip of ore-shoots was understood at this time in relation to 

 the direction of veins. " Every vein (gang) has two (outcrops) ausgehen, one of the 

 " ausgehen is toward daylight along the whole length of the vein, which is called the ausgehen 

 " of the whole vein. The other ausgehen is contrary to or toward the strike {streichen) of 

 " the vein, according to its rock (gestcin), that is called the gesteins ausgehen; for instance, 

 " every vein that has its strike from east to west has its gesteins ausgehen to the east, and 

 " vice-versa." 



Agricola's classification of ore-deposits, after the general distinction between alluvial 

 and in situ deposits, is based entirely upon form, as will be seen in the quotation below relating 

 to the origin of canales. The German equivalents in the Glossary are as follows : — 



Fissure vein {vena profunda) Gang. 



Bedded deposit (vena dilatata) Schwebender gatig oder fletze. 



Stockwerk or impregnation (vena cumulata) Geschute oder stock. 



Stringer (flhra) Klufft. 



Seams or joints (commissurae saxorum) Ahsetzen des gesteins. 



It is interesting to note that in De Natura Fossiliiim he describes coal and salt, and 

 later in De Re Metallica he describes the Mannsfeld copper schists, as all being venae dilatatae. 

 This nomenclature and classification is not original with Agricola. Pliny (xxxni, 21) uses 

 the term vena with no explanations, and while Agricola coined the Latin terms for various 

 kinds of veins, they are his transliteration of German terms already in use. The Niitzliche 

 Berghiichlin gives this same classification. 



Historical Note on the Theory of Ore Deposits. Prior to Agricola there were 

 three schools of explanation of the phenomena of ore deposits, the orthodox followers of the 

 Genesis, the Greek Philosophers, and the Alchemists. The geology of the Genesis— the 

 contemporaneous formation of everything — needs no comment other than that for anyone to 

 have proposed an alternative to the dogma of the orthodox during the Middle Ages, required 



^he Latin vena, " vein," is also used by the author for ore ; hence this descriptive 

 warning as to its intended double use. 



