334 New Cobalt Minerals. 



Sulphur, - - - - 17.7 



Arsenic, - - - - 47.4 



Scheerer found in two crystals 8.3 and 6.5 parts of cobalt. 



We may name this spieces to distinguish it from the common 

 Arsenic-pyrites, cobalt-arsenic-pyrites. 



In all the crystals examined by me, a circumstance was re- 

 marked, which Scheerer has not mentioned, that the apparently 

 purest and best formed crystals were more or less penetrated with 

 clear crystalline quartz, the quantity of which in some specimens 

 made up almost a quarter of the weight, in which case the in- 

 ternal structure could be seen on the outside. This comming- 

 ling remained in all the crystalline portions, even when the whole 

 crystal was dissolved in aqua regis. Besides, there remained 

 small black spangles, still undissolved, which had altogether the 

 appearance of graphite, and are in fact nothing else. I have also 

 observed in this undissolved residuum still a third mineral, in 

 very hard, brownish yellow, but quite microscopic crystals, which 

 is certainly not quartz, but nothing could be determined concern- 

 ing its nature. 



The second mineral, with limewhite color mingled with lead 

 gray, very definitely distinguished from that of arsenical-cobalt, 

 and which occurs both compact with scaly grooves and beautifully 

 crystallized in tesseral forms, the crystals oftener growing together 

 with crystals of cobalt-glance, is arsenical-cobalt with J more 

 arsenic than usual. According to my analysis, it contains, 



Hayes of Roxbury, (Vol. sxiv, p. 387, this Journal.) Dr. Dana describes it as 

 occurring in crystals analogous, if not identical with those of mispickel ; and Mr. 

 Hayes found their Sp. Gr. = 6.214, according to the analysis of the latter it 

 contains, 



Sulphur, 17.84 



Arsenic, - - - - - ' - 41.44 



Iron, 32.94 



Cobalt, - - - - - - - 6.45 



98.67 

 Loss partly iron. 

 Mr. Hayes proposed for it, the name of Danaite. Henry examined and de- 

 scribed numerous forms of this ore from Franconia (see my treatise.) I perceive 

 no sufficient reason for separating it from mispickel, with which it agrees in every 

 respect save in the substitution of a small per-centage of cobalt for iron. 



The second variety of cobalt ore, described by Scheerer and Wohler does 

 not appear to differ from the normal varieties of sraalentine (arsenical-cobalt.) 



C. U. Shepard. 



