418 W. Lindgren — Orthoclase as a gangue mineral. 



Art. L. — Orthoclase as gangue mineral in a fissure vein; 

 by Waldemar Likdgren. 



[Published by permission of the Director of the U. S. Geological Survey.] 



The occurrence of feldspars as gangue minerals in fissure 

 veins is not common. But on the other hand many well- 

 authenticated instances make it certain that they may be 

 formed during the conditions attendant upon the deposition of 

 ordinary fissure veins, i. e. by aqueous deposition. Lime feld- 

 spars or soda lime feldspars appear to occur very rarely, the 

 only known instance being that described by the author from 

 Grass Yalley, Cal.* Even this case could not be as completely 

 demonstrated as would have been desirable. Albite is more 

 common. While it is only rarely mentioned from European 

 mineral deposits, it has been described as occurring in places 

 very abundantly in Australian gold quartz minesf as well as in 

 similar veins in the province of Minas Geraes, Brazil. In the 

 United States, albite has been noted from several places. 

 Genth describes it from the Steele mine, North Carolina, in 

 the Appalachian gold belt. In California it was first noted by 

 Genth in 1859 from Winters gold vein, Calaveras County.;); 



Albite was also described by Wendell Jackson from Stanis- 

 laus mine, Calaveras County, and lately again by EL. W. Turner 

 from the Shaw mine, El Dorado County. The mineral will 

 probably be found in many other places in the vicinity of the 

 mother lode. It was recently noted by the author in speci- 

 mens from the Gentle Annie mine, near Placerville. In spite 

 of very careful search no albite has yet been recognized from 

 Nevada City or Grass Yalley. 



Orthoclase has been described from several European ore 

 deposits, generally having the crystallographic forms and char- 

 acteristics of adularia. Thus, we find it recorded§ from Schmie- 

 deberg and Kupferberg in Silesia, Himmelfahrt mine near 

 Freiberg in Saxony, Schlaggenwald in Bohemia, Felsobanya 

 and Schemnitz in Hungary. Also from Transylvania at 

 Botesbanya, Cseb, and Yerospatak. Most of the occurrences 

 in the latter two countries are from gold quartz veins. Every- 

 where, however, the orthoclase is more of a mineralogical 

 rarity than an abundant gangue mineral. 



Breithaupt described, without detailed notes as to its occur- 

 rence, an orthoclase of adularia habit from the • Yalenciana 



* 17th Ann. Rept., U. S. G. S.. p. 87.. This feldspar occurs on small stringers 

 differing in character from the typical gold quartz veins from that locality, 

 f G.. Ulrich, Min. Vict., 1866. 



X G. F. Becker, 16th Ann. Kept. U. S. G. S., Part 3, p. 278. 

 § Hintze, Handbuch der Mineralogie, p. 1361. 



