Genth.] 



38 



[March 18, 



Analyses of vanadinite. a, 1 and 2 by H. F. Keller ; c by myself. 



a, 1. a, 2. c. Brownish olive 



Brownish. Bright orange-red. green from 



Yavapai County. 



Sp. grav. 

 CI 



Fe,03 

 CuO 

 PbO 

 V,05 



P2O5 



Less O, equiv. to CI. = 



From Mammoth Mine 

 6.572 — 



2.41 

 0.48 



77.49 



16.98 



3.06 



0.29 



100.71 

 0.55 



100.16 



— 2.46 — 



77.47 



17.16 



4.30 



trace 



101.39 

 0.56 



100.83 



7.109 

 2.69 



0.04 



0.18 



77.96 



18.64 



trace 



0.73 



100 23 

 0.61 



99.62 



Ti. Variety of Desdoizile, Cvprodescloizite, Ramirite, Tritochorite. — In 

 1883, Samuel L. Penfield (Am. Journ. Sc. [3] xxvi, 361) published the 

 description and analyses of a mineral from Mexico as a variety of des- 

 cloizite ; at about the same time, C. Rammelsberg (Berl. Acad., Berl., 1883, 

 1215), under the name cuprodescloizite gave his analysis and description of 

 the same mineral from San Luis Potosi in Mexico. In a pamphlet, "La 

 Ramirita, niteva especie mineral, Mexico, 1885," D. Miguel Velasquez de 

 Leon gave the same mineral the name ramirite, with an engraving show- 

 ing its appearance and an analysis of the same. 



In his paper Mr. Penfield referred to the great similarity of the ap- 

 pearance and the results of the analyses of his mineral with those of Fren- 

 zel's tritochorite. About two years ago Prof F. W. Clarke presented to 

 me a specimen of ramirite from San Luis Potosi, Mexico, and a year ago 

 I had an opportunity to purchase, from Dr. A. E. Foote, a number of 

 pieces which gave such an abundance of very pure material that I thought 

 a re-examiuation desirable on account of great discrepancies in the 

 amounts of water and the pentoxides of arsenic and vanadium as well as 

 cupric oxide. 



The mineral occurs as an incrustation from 1 or 2 to 10™" in thick- 

 ness, radiating fibrous to fine columnar. The form of the individual 

 crystals cannot be distinguished, they are united into groups resembling 

 the arrangement of cockscomb barite or prehnite. The color is dark yel- 

 lowish-brown, and the surface has a dark color, and a velvety appear- 

 ance ; the fracture has a resinous lustre. Powder pale yellow. The spec^ 

 grav. = 6.203. 



