JOURNAL 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. VII JUNE 19, 1917 No. 12 



MINERALOGY. — Aurichalcite from Big Cottonwood Canyon, 

 Salt Lake County, Utah. A. Ledoux, University of Brussels. 

 (Communicated by T. L. Walker.) 



The mineral aurichalcite was first given rank as a distinct 

 species in 1839 by Bottiger. Prior to that time it was recog- 

 nized as early as 1788 under the name "calamine verdatre" bj r 

 Patrin, who mentioned that this variety of calamine contained 

 "une bonne quantite de cuivre." 



On account of the character of the mineral, previous inves- 

 tigators have worked at a decided disadvantage in determining 

 the crystal system to which this mineral belongs, and the writer 

 has labored under some of the disadvantages that in the 

 past prevented the most accurate determination of the crystal 

 constants. 



A brief resume of the crystallographic work that has been 

 done on the mineral follows: 



In 1874 Des Cloizeaux 1 described aurichalcite as acicular 

 crystals of undetermined form. 



In 1890 Albin Belar 2 considered the mineral as monoclinic 

 with 0=0 and a : b : c = 1 : x : 0.7208. He states that the 

 plates of the mineral are parallel to the principal cleavage taken 

 as 010, the side GH of the triangle (fig. 1) being the combination 

 of 010 and 100, the hypotenuse GI being the edge between 



1 Manuel de Mineralogie, 2: 183. 1874. 



2 Ueber Aurichalcite. Zeitschr. fur Krystallographie, No. 17. 1890. 



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