Qenth.] 



28 



[March 18, 



State of Jalisco. Professor 6. vom Rath, in his " Geologische Brlefe 

 SCALT T' / ^"^ Amerika" (Sitzungsberichte der 



Niederrheinischen Gesellschaft fiir 

 Natur und Heilkunde in Bonn, July 

 7th, 1884), mentions it as woodtin, 

 implanted in red porphyry in the 

 Valle San Francisco, San Luis Po- 

 tosi, also between Sta Rosa and La 

 Fragua, in Gnanaxuato, and at Sain 

 Alto and several other localities in 

 the Sierra Zacatecaua. 



The following analyses of the red 

 variety were made : * 



1. Bright brick-red, fine granular, 

 somewhat reniform, the surface assu- 

 ming slightly fibrous crystalline ap- 

 pearance. Durango ; from my Cabi- 

 net, 1, a and b. 

 3. Reniform, curved lamellar, the laminse from 0.1 to 1°"" in thick- 

 ness, separate on breaking with smooth surface slightly granular, brick- 

 red; powder bright brick red. Coneto, State of Durango; from Mr. 

 Joseph Wharton, XL 



3. Large pebble, somewhat granular, of the appearance of compact 

 hematite, powder brick red. Durango ; from Mr. Clarence S. Bement, III, 



4. A mass which had deposited as an incrustation upon quartz or a 

 siliceous rock, of a thickness of 20"""", with fine crystalline fibrous structure, 

 being flat on the bottom and reniform on the surface. Dark brown, a fresh 

 fracture reddish brown, powder brownish brick-red, Coneto, Slate of 

 Durango ; from Mr. Joseph Wharton, 17. 



5. Stalactitic, granular, the surface covered with minute crystals, color 

 and powder bright brick-red. Minute crystals of hematite were implanted 

 which were separated by a magnet (this hematite being slightly magnetic) ; 

 from the ores No. 1 of Mina del Diablo, V. 



6. Botryoidal, dark brown, on fracture paler reddish-brown, with a 

 slightly fibrous structure ; color of powder terra cotta ; from Guanajuato, 

 State of Guanajuato, from Mr. Clarence S. Bement, IV. 



* Artificial Pj/rite—ln the analj'sis it was found to bs most convenient to render the 

 cassiterite soluble by fusing with a mixture of sodium carbonate and sulphur, at first 

 at a very low temperature, and then for about ten minutes at low red heat. There was 

 rarely more than a few milligrams of cassiterite left unacted upon which yielded readily 

 to a second fusion. Thus all the tin and arsenic, and the greater part of the iron dis- 

 solved in water as sulpho-salts of sodium. In two instances in Analyses III and V b, I 

 was interrupted in my work and the fusion at a low temperature was continued for five 

 or six hours. When the mass was treated with water it dissolved with a yellowish-red 

 color without dark green tint, and the washings also did not indicate that any iron so- 

 dium sulphide had gone in solution. Ths insoluble residue, however, showed the iron 

 in the form of octahedral crystals or clusters of crystals of pale brass-yellow pyri.te. 



