Analysis by Ebelmen (Ann. des Mines, [4,] xij 47) : 



s 



27-25 



Sb 



As 



Cu 



Fe 



Zq 



un 



9-12 



41-57 



4-66 



2-24 



99-61. 



Specific gravity 4-749; occurs in highly modified dodecahedral 



crystals. 



Dioptase. — Dioptase (Smaragdo-chalcite) is announced by F. 

 Sandberger (Pogg, Ann., Ixxxii, 133,) as occurring in a sand- 

 stone containing Spirifers in the Duchy of Nassau, betwen Ober- 

 lahnstein and Braubach. 



'/ 



■>/■ 



Shepari>5 (Proc. Amer. Assoc, New Haven, p. 322.) — A dull 

 verdigris green mineral containing carbonic acid occurs upon the 

 vitreous copper ore of Bristol. Prof Shepard observes that if 

 when more fully examined it proves to be a definite chemical 

 compound, as he now suspects, it will then be proper to bestow 

 upon it a mineralogical name, j. b- d. 



{To he continued.) 



Art- XXV. — Notice of the Report on the Geology and Topogra- 

 phy of a portion of the Lake Superior Land District /* by 

 J. W. Foster and J. D. Whitney. 



The district embraced within the Report of Messrs. Foster and 

 Whitney covers an area of 16,000 square miles, and nearly the 

 whole of it is still an unbroken wilderness. The opening of the 

 Michigan Copper mines has given it a peculiar economical inter- 

 est, and, more than this, it has a high geological importance, 

 hardly exceeded elsewherej on account of the singular character 

 of the mineral region, the structure and relations of the rocks in 

 different parts, and the display of the phenomena of drift. The 

 investigations in the same rearion. made bv Dr. C. T. Jackson, 



Land District, in the State of Michigan ; by J. W. Foster and J. D. Whitney, United 

 States Geologists. In two parts. Parti, Copper Lands, 244 pp. 8vo, with 12 

 plates and several maps. "Washington, 1850. 81st Congress, 1st Session, Ex- 

 Doc No. 69. ' 



222 Notice of Messrs. Foster and Whitney'^ s Report 



(Pogg. Ann., Ixxx, 400,) 5io 37-65, ?b 62-35-10000. The 

 crystals are of a light yellow color. 



Mimelene of the Mine Azulaqaes in Zacatecas. — Dr. C. Berge- 



mann obtained in an analysis (Pogg., IxxX; 401;) 



tb Is ■ Cl 



^4-961 23065 2-445 = lOO^Yl, 



giving the formula PbCl+3tb»ls. This corresponds to Arsenic i 



acid 23 065, oxyd of lead 66-948, chlorine 2-445, lead 7*140. 



+ 



Gray Copper from the foot of the ridge Mouzaia in Algiers, 



