Mineralogy of South America, 135 



Tennantite, 4(Cu 3 Fe) S+As 2 S 3 . 

 Tetrahedrite,4(Cu 2 AgFeZn)S + (AsSb) 2 S : 

 Thenardite, NaO SO 3 . 

 Trona, 2NaO,3C0 2 . 

 Tourmaline, (3RO, R 2 O 3 ) (B Si) O 3 . 

 Uralite, 3 RO, 2 Si0 3 + RO, SiO 3 . 

 Vanadinite, 9PbO, Vd0 3 +PbCl. 

 Vanadinite (cupreous). 



Vivianite, 3FeO, P0 5 + 8HO. 



Wad,Mn0 2 +HO. 



Wulfenite, PbO MO 3 . 



Zincblende, ZnS. 



Zincblende (auriferous). 



Zincblende (cupriferous). 



Zincblende (plurnbiferous),3ZnS+2PbS. 



In the classification of these minerals the following arrange- 

 ment will be employed as fulfilling all necessary conditions : — 



1. Minerals of meteoric origin. 



2. Minerals the products of active volcanoes. 



3. Minerals of the recent or unconsolidated surface-deposits. 



4. Minerals of the tertiary formations. 



5. Minerals of the post-cretaceous basaltic dykes. 



6. Minerals of the post-oolitic diorite eruptions, and their 

 accompanying metallic veins. 



(a) Minerals resulting from the mutual reactions and alte- 

 ration of the above under the influence of air, fresh and 

 sea-water. 



7. Minerals of the great oolitic porphyrite eruptions with their 

 interstratified tuffs, and other contemporaneous beds. 



(a) Mineral products of the decomposition and alteration 

 of do. 



(b) Minerals specially developed in these rocks at the points 

 of contact with the intrusion of the* before-mentioned 

 Diorite and basalt. 



8. Minerals of the post-Silurian auriferous granite eruptions 

 and accompanying metallic veins. 



(a) Mineral products of the alteration of above. 



9. Minerals of the metamorphic rocks of pre-Devonian age. 

 (a) Minerals specially developed in these rocks at the point 



of contact with the granite intrusions. 

 It may here be remarked that the greater part of Chile seems 

 to have been above water from the Silurian to the Liassic period*, 

 and again from the Neocomian to the period of the deposition 

 of the older tertiary formations on that coast. 



(1) Minerals of Meteoric Origin. 



In the aerolites known to have fallen in Chile are found 

 only 



Peridote. Schreibersite. 



Nickel iron. Protosulphide of iron. 



* Traces of apparently Triassic rocks are, however, found, especially in 

 the north of Chile, which become more strongly developed still further 

 northwards in Bolivia and Peru. 



