PROPYLITE, 81 



Section 3 . (Chapter III.) 

 PROPYLITE. 



Historical statement. — The term propylite, as is well known, was introduced 

 into lithology by Baron F. v. Richthofen, mainly in consequence of observa- 

 tions made in the Carpathians and in the States of California and Nevada. In 

 his memoir on "The Natural System of Volcanic Rocks "^ greater prominence 

 is given to the Washoe occurrence than to any other. From his description 

 of the rock the following statement of its characteristics is taken almost 

 verbatim. Propylite is always porphyritic, and no prominent property dis- 

 tinguishes it from porphyritic diorite. The feldspars are oligoclase and the 

 hornblendes ordinarily dark-green and fibrous. The groundmass is usually 

 green and appears to owe its color to the profuse dissemination of small 

 particles of fibrous hornblende. It also presents a peculiar and recog- 

 nizable, though hardly describable, appearance or habitus. It is extra- 

 ordinarily rich in mineral veins, both in Europe and in America. Geo- 

 logically it is the earliest of the Tertiary volcanic rocks. Mr. Clarence 

 King^ accepted Baron v. Richthofen's determination of propylite in the 

 Washoe District (a region which he visited in company with that geologist), 

 though with some limitations and additions. Outside of this District the 

 geologists of the Exploration of the Fortieth Parallel found only a few 

 obscure localities of the rock. In 1876 Prof F. ZirkeP confirmed the 

 independence of propylite as the result of a microscopical examination of 

 the collections of the Exploration of the Fortieth Parallel. In 1880 Capt. 

 C. E. Dutton^ announced the presence of considerable areas of propylite 

 in Utah. 



'Mcni. Cal. Acad, of Sciences, Vol. I., Part II. '^Exploration of the Fortieth Parallel, Vol. III. 

 'Ibia., Vol. VI. -"The High Plateaus of Utah. 



6 C L, 



