ACADEMY OF NATURAL SCIENCES. 287 



Professor Whitney read the following : 



Notice of the Occurrence of a Tungstate of Lime and Copper 



in Lower California. 



BY J. D. WHITNEY. 



Among some specimens brought from the vicinity of La Paz, Lower Califor- 

 nia, by Mr. Remond, about three years since, was one which attracted my 

 attention, as it seemed to contain an undescribed mineral. 1 therefore made 

 an analysis of it and found it to consist of tungstic acid, oxide of copper, and 

 lime, with a small quantity of water, probably not essential to its composition. 

 The results of the analysis were as follows : 



Tungstic Acid 79.69 



Oxide of Copger 0.77 



Lime , WW 



Protoxide of Iron . . - 31 



Water 1.40 



99.12 



On examining to ascertain if there was any known mineral having a compo- 

 sition similar to this, I found that a tungstate of lime containing copper had 

 been described by Domeyko as occurring in the copper mines of Llamuco, near 

 Chuapa, in the province of Coquimbo, in Chili, where it was discovered by ftl. 

 Gay '( Annates des Mines (4) iii, 15). That mineral, however, only contained 

 3.3 per cent, of oxide of copper, while the one of which the analysis is given 

 above contains 6.77 per cent, of that substance. M. Domeyko calls the mineral 

 analyzed by him " Scheelin calcaire cuivreux," but does not attempt to give 

 a formula for it, or to decide whether it is entitled to rank as a distinct species. 



The Lower California mineral, of which the analysis is given above, occurs 

 in a red metamorphic rock, associated with black tourmaline. It is crystalline- 

 granular in structure, with a distinct cleavage in one direction, and seems to be 

 homogeneous throughout. Its hardness is about that of Scheelite ; luster, highly 

 vitreous ; streak, very light greenish-gray ; color, pistachio green, passing to 

 olive and leek green. Before the blowpipe in the glass tube it. blackens, 

 and gives off a little water. On charcoal it blackens instantly, becomes 

 rounded on the edges, with a little intumescence, and gradually acquires the 

 appearance of a slag, in which numerous fine points of metallic copper are seem 

 With the fluxes it gives the reactions of tungstic acid and copper. It is easily 

 dissolved by chlorohydric acid, with separation of tungstic acid. 



From the appearance of the mineral, I am inclined to regard it as having a 

 definite" composition, represented by the formula CuO W0 3 -f 2 (CaO W0 3 ) ; 

 this formula would require the following composition : 



Tungstic Acid 78.43 



Oxide of Copper 8.95 



Lime 12. 62 



100.00 



