CLASSIFICATION OF IGNEOUS ROCKS 53 



consist only of quartz and an auxiliary mineral, such as mica, 

 tourmaline, topaz, etc. Among these are: 



Esmeraldite Spurr. The terms greisen and beresite 

 have been used more or less loosely for quartz-muscovite rocks, 

 although, as mentioned above, they have other meanings. Spurr^ 

 definitely applied the term esmeraldite to rocks from the southern 

 Klondike district, Esmeralda County, Nevada, which consist only 

 of quartz and muscovite. 



Syn.: Greisen (in part), Glimmer-greisen Jokely.^ 



Tourmalite.^ This term is here suggested for rocks 

 consisting only of tourmaline and quartz, to which the name 

 hydrotourmalite was given by Daubree.'' Other synonyms are 

 Schorlquarzit, Schorlfels, Schorlschiefer, Turmalinschiefer, Turma- 

 linfels, schorl-rock, Carvoeira,^ etc. 



Topazite. Topazite is here suggested for rocks con- 

 taining only quartz and topaz. 



Syn.: Topasfels Werner,^ Topazogene Charpentier,^ 

 topaz-rock. 



(in) Orthotarantulite. The prefix "ortho-" is used here and 



in all of the hinge families to indicate feldspathic rocks which con- 

 tain less than 5 per cent plagioclase. They include, therefore, 

 orthoclase, microcline, microperthite, and anorthoclase rocks. See 

 note under (112). Thus defined, orthotarantulite is a tarantulite 

 with less than 5 per cent of its feldspar plagioclase. 



'J. E. Spurr, "The Southern Klondike District, Esmeralda County, Nevada," 

 Econ. GeoL, I (1906), 382. 



"Johann Jokely, "Das Erzgebirge im Leitmeritzer Kreise in Bohmen," Jahrb. 

 d. k. k. geol. Reichsanst., IX (1858), 566. 



3 In the following pages proposed new names are in bold-face type. Where the 

 prefix indicates a newly formed group it is shown thus, orthogranite. 



■•M. Daubree, "Sur le gisement, la constitution et I'origine des amas de mineral 

 d'etain," Ann. d. Mines, XX (1841), 84. 



5 W. L. V. Eschwege, Beitrage z. Gebirgskunde Brasiliens (1832), p. 178. 



* A. G. Werner, Kurze Klassification und Beschreibung der versckiedener Gehirgs- 

 arten (Dresden, 1787), p. 15. 



7 J. de Charpentier, Vom Schneckenstein, oder dem sdchsischen Topasfelsen (Prag, 

 1776). 



