CLASSIFICATION OF IGNEOUS ROCKS 223 



(3310) Mela-quartz-gabbro. Too awkward a term. There 

 are three rocks in this family, but all of them are melanocratic 

 hornblende-quartz-gabbros — an "abnormal hornblende-gabbro" 

 in the Moyie sill described by Daly/ a quartz-bearing gabbro from 

 the Purcell sill, also described by Daly,^ and a hocnblende-gabbro 

 from Sepanlampi, Hauksuo, Kisko, described by Eskola.^ The 

 t)^e of the family should be chosen from an augite rock. 



(3314) Melamonzogabbro. See note under (2314). Here are 

 included two essexites, a hornblende-gabbro, a hornblende-no rite, 

 and a so-called gabbro. 



(3315) Melagabbro. See note under (2315). Many gabbros 

 fall here, also a few norites, and some diabases and basalts (and 



"dolerites"). 



Melabasalt. The extrusive equivalent of the above. 

 Arapahite Washington and Larsen'' belongs here. 

 (3317) Labradorite-(bytownite-)shonkinite. See note under 



(3217)- 



(3324) Mela-nephelite-monzogabbro. See note under (2324). 



(3325) TheraUte Rosenbusch. Therahte, from the Greek 

 drjpav ("eagerly looked for"), was apphed by. Rosenbusch^ to 

 plagioclase-nephelite rocks first thought to be represented by certain 

 tephrites and basanites described by Wolff. ^ True therahtes, 

 however, were first described by Wolffs some years later. Besides 

 the presence of plagioclase and nepheHte, these rocks are character- 

 ized by much predominating dark constituent; consequently 

 they belong to Class 3. Among the Hme-soda feldspars of the rocks 



'Reginald A. Daly, "Geology of the North American Cordillera at the Forty- 

 ninth Parallel," Geol. Surv. Canada, Mem. 38, Part I (191 2), p. 234. 



'Ibid., p. 224. 



3 Pentti Eskola, "On the Petrology of the Orijarvi Region in Southwestern Fin- 

 land," Bull. d. I. com. geol. d. Finlande (Helsingsf ors) , 1914, p. yi- 



1 Henry S. Washington and E. S. Larsen, "Magnetite Basalt from North Park, 

 Colorado," Jour. Wash. Acad. Sci., Ill (1913), 452. 



sH. Rosenbusch, Mikroskopische Physiographie der massigen Gesteine (2d ed.; 

 Stuttgart, 1887), p. 248. 



6 J. E. Wolff, "Notes on the Petrography of the Crazy Mts., and Other Localities 

 in Montana Territory," Northern Transcontinental Survey (1885), pp. 8-13. 



7 J. E. Wolff, "On the Occurrence of Theralite in Costa Rica, Central America", 

 Amer. Jour. Sci., I (1896), 271. 



