loo PROCEEDINGS OP THE ACADEMY OF 



bably of a ganoid fish, which I obtained from the black shale, of what have been 

 usually considered the triassic rocks, from near Phoenixville, Chester Co., Pa. 



The dental bone is 20 lines long, by 4 lines in depth posteriorly. It is straight, 

 and its outer surface is covered with fine, interrupted ridges, such as are ob- 

 served upon small ganoid scales, found in the same series of rocks at Gwynned, 

 on the North Pennsylvania Railroad. 



Upon the dental border of the specimen there may be counted the remains of 

 20 teeth, situated at irregular distances apart. They have measured from ^ to 1 

 line long. They are columnar in form, slightly curving inward ; have a spread- 

 ing base ; and an abrupt, conical, enamel summit. The fish may be allied to 

 Belonostomus or Eugnathus, but I am unable to ascertain the exact form of the 

 teeth in these genera. 



4. Pycnodus robustus, Leidy. 



The species is founded upon a single large tooth obtained by Prof. G. H. Cook, 

 from the green sand of New Jersey. 



The specimen is 14^ lines long and 3| wide. 



Examination of ENABGITE from New Grenada. 



BY WM. J. TAYLOR. 



I received from Jos. A. Clay, Esq., a fellow member of the Academy, a raice- 

 ral which proves on examination to be Enargite. Mr. Clay received this in a 

 box of minerals from South America; it was labelled " an antimonial silver ore 

 from the mines of Santa Anna, New Grenada ;" there were several other min- 

 erals accompanying it from the same locality. 



Enargite was, I believe, first found in the Cordilleras of Peru, and mineral- 

 ogists were surprised a few weeks since by Dr. Genth's determining a small 

 specimen of a mineral found by the State Geologist of South Carolina, Oscar 

 M. Leiber, Esq., from the " Brewers' Mine," to be of the same species. (" Contri- 

 butions to Mineralogy," by Dr. F. A. Genth, American Journ. Sci. and Arts, 

 May, 1857, p. 420.) The fact of its occurring at another locality will not be 

 without interest. 



The structure of the massive portion of the mineral is columnar, and it is 

 intermixed with a quartose rock and pyrites, in which small cavities occur, 

 filled with the crystalled Enargite, some of which are very distinct. The 

 Enargite is very brittle, its color a greyish black with streaks of the same color ; 

 the powdered mineral is very crystalline with a metallic lustre. Before the 

 blowpipe it decrepitates ; on charcoal, gives the odor of arsenic and a very 

 slight incrustation of antimony ; with carbonate of soda, gives hepar and 

 metallic copper. 



The analysis I made in the laboratory of Dr. F. A. Genth, from a small por- 

 tion of the perfectly pure massive mineral, of which O*7082 grammes wprt- 

 treated with aqua regia and gave the following results ; 



Per cent. 



Sulphur 34.50 



Copper 46.62 



Arsenic 16.31* 



Antimony 1.29 



Iron 0.27 



98.99 

 The atomic proportion is : 



Sulphur 2.16 



Copper 1.47 



^'■««°'<= "> 0.23 



Antimony j 



♦There was a slight Joss of the arsenic. 



[June, 



