HANDBOOK FOR THE DEPARTMENT OF GEOLOGY. 581 



Hornblende andesite : Pelican Peak, Wyoming, 28900 and 28901; north end of Mouo 

 Valley, Nevada, 35497; Mountain Pass, between Bodie and Mono Lake, 35469; 

 MnUin's Ranch, west shore of Pyramid Lake, Nevada (propylite), 35323 ; Washoe 

 District, Nevada, 24001,24020, 24026, 24121; south slope Sepulchre Mountain, 

 Yellowstone National Park, 72860; road from Ennis to Virginia City, Madison 

 County, Montana, 72867 ; Mount Shasta, California, 38362 and 36977 ; Bogosloff 

 Island, Alaska, 36855 and 37033; Buckskin Gulch, Colorado (propylite), 36414; 

 Oaxaca, Mexico, 37762 ; Mexico, Mexico, 37770 ; Ixtapalapa, Mexico, 37711 ; the 

 Siehengebirge, Prussia, 34579, 34580, 34581, 36400 to 36406 inclusive ; Sengelherg, 

 near Salz, Nassau, Germany, 36409; Dahlen, Nassau, Germany, 36407; Wolfer- 

 ding, Nassau, Germany, 36408; Gyalu, Transylvania, 36411 ; Coin Neograd, Hun- 

 gary, 34585. 



Hypersthene andesite : Mount Shasta, California, 36978 and 38363; ibid, (pumiceous) 

 36979; Mono Craters, California, 37216; Zacatecas, Mexico, 37707; Mexico, Mex- 

 ico, 37712 ; Volcano of Krakatoa (pumiceous), 35516. 



Mica andesite : *Geisberg in the Siehengebirge, Rhenish Prussia, 36393 ; Dilln, Repis- 

 tye, Kremnitz, Tepla, and Schemnitz, Hungary, 36394, 36395, 36396, 36398, 36399, 

 70182, 70185 ; Monte di Capucini, near Viterbo, Italy (with hyperstheue), 36397. 



Augile andesite : Southeast side of Mono Lake, near Mono Springs Station, California, 

 35439; west side Humboldt Valley, 35465; Washoe District, Nevada, 24018; near 

 Fort Ellis, Gallatin County, Montaua, 38577 ; South Boulder Creek, Montana 

 (with hypersthene), 73167; Kremnitz, Hungary, 34577, 36484 and 36486; Nagy 

 Banya, Hungary, 36485; Schemnitz, Hungary, 36116, 36482, 34576, 34578; Tokaj, 

 Hungary (with hypersthene), 36487; Bath, Hungary (spherulitic, with hypers- 

 thene), 36488; Bagonya, Hungary (with hypersthene), 36489; Kis Kapus, tran- 

 sylvania, 36483 ; Monte St. Croce, Roccamonfina, Italy (with mica), 73021. 



8. The melaphyrs and augite porphyries. 



The term melaphyr is used by Rosenbusch to designate a volcanic 

 rock occurring in the form of intrusive sheets and lava flows, and con- 

 sisting essentially of a plagioclase feldspar, augite and olivine, with free 

 iron oxides and an amorphous of porphyry base. The augite por- 

 phyrites differ in containing no olivine. The rocks of this group are 

 therefore the porphyritic forms of the olivine bearing and olivine free 

 diabases and gabbros, differing from these in structure, in mode of 

 occurrence, and in belonging in great part to the Carboniferous and 

 older Permian formations. 



Structure. — As above noted they are porphyritic rocks with, in their 

 typical forms, an amorphous base, are often amygdaloidal, and with a 

 marked flow structure. 



Colors. — In colors they vary through gray or brown to nearly black ; 

 often greenish through chloritic and epidotic decomposition, as shown 

 in specimens No. 35940, from Brighton, Massachusetts. 



Classification and nomenclature. — According as olivine is present or 

 absent they are divided primarily into melaphyrs and augite porphy- 

 rites, the first bearing the same relation to the olivine diabases as do 

 the quartz porphyries to the granites, or the hornblende porphyrites to 

 the diorites, and the second a similar relation to the olivine free dia- 

 bases. The augite porphyrites are further divided upon structural 

 grounds into (1) diabase porphyrite, which include the varieties with 



