Scientific Intelligence. 





S 



Bi 



Pb 



Ag 



Cu 



Gangue. 



1. 



15-21 



32-62 



43-94 



5-78 



tr. 



0-15 = 97-70 



2. 



15-27 



33-31 



44-28 



5-49 



0-03 



0-14=98-52 



3. 



15-19 



33-89 



44-03 



5-72 



tr. 



0-17 = 99-00 



The bismuth determinations are regarded as somewhat low, and 

 in (2) and (3) there was probably also a loss of lead. The general 

 formula derived 3PbS + Bi,,S 3 is that of Kobellite, but the variety 

 is interesting in containing a considerable amount of silver, while 

 the antimony is absent.— Journ. Amer. Chem. Soc, vol. vii, No. y J. 



13. Crystallographic Notes ; by Oliver W. Huntington. — 

 Mr. Huntington has made a study of the beautiful crystals of 

 azurite from Clifton, Arizona. The}- resemble the crystals from 

 Chessy in habit, and agree closely in angles also, although not 

 often admitting of the most exact measurement. They are quite 

 highly modified although not adding to the already long list of 

 known planes. The planes present were fifteen in number with 

 001, 101 prominent. 



The same writer gives the results of some measurements of the 

 compound quartz crystals from Albemarle County, Virginia, de- 

 scribed by Prof. W. G. Brown in this Journal(Sept., 1884). He 

 finds that out of a very large number of apparent twins there 

 were only three cases in which the faces of two individuals fell abso- 

 lutely in the same zone, and in which an assumed twinning-plane 

 could be referred to probable axial ratios. The possible twin- 

 ning-planes in these cases were —£%I£, — T 3 T i2, —^M. The con- 

 clusion seems to be, therefore, that the grouping is rather acci- 

 dental, as in many other cases that have been described, than 

 according to a definite law. — Proceedings of the American Acad- 

 emy of Arts and Sciences, June 10, 1885. 



14. Mineralogical Notes; by Geo. F. Kuntz. — In a paper read 

 before the Ann Arbor Meeting of the American Association for 

 the Advancement of Science, Mr. Kunz presented several points 

 of interest in regard to American minerals. A description was 

 given of a pseudomorph from Magnet Cove, Arkansas, having 

 the form of trapezohedral crystals varying in size from 10 to 

 45 mm. They resemble the melanite of the same locality, but 

 so far as examined do not show the clodecaheclral faces. The 

 color varies from yellowish-brown to grayish-white, and the 

 specific gravity of the more compact specimens was 'J "44 (near 

 that of leucite). Upon fracture an external shell separates from 

 a core of trapezohedral form. A mici-oscopic examination by 

 Mr. G. P. Merrill showed that the structure was homogeneous, 

 but for the most part spherulitic, though beyond the center there 

 was a zone made up of radiating columnar bodies with indefinite 

 outline ; except in shape there was no distinguishing feature 

 between the outer crust and the more compact interior. The 

 microscopic examination did not lead to any definite conclusion 

 as to the original mineral. An analysis by Dr. F. A. Genth 

 afforded (mean of two) : 



Si0 2 A1 2 3 Fe 2 O s MgO Na 2 K 2 H 2 

 (|) 60-77 22-13 0-44 0'05 0-36 13-91 2-95 = 100-61 



