BOLEITE, NANTOKITE, KERARGYRITE AND CUPRITE. 97 



Copper 64-18 (with at. wt. of 63-17) 



Chlorine 35-82 (with at. wt. of 35-37) 



100-00 



At the time of making this examination only small portions of 

 the mineral was available. S. G. (approx.) 4*3, Insoluble in 

 water, soluble in ammouia, hydrochloric acid and solution of 

 common salt ; on heating with water in presence of air, it is 

 decomposed ; lemon yellow coloured hydrated sub-oxide of copper 

 being precipitated, which on further heating is changed into red 

 anhydrous sub-oxide, part of the copper going into solution as 

 cupric chloride." 



The properties of the specimens forwarded to me correspond 

 with those given by Messrs. Armstrong and Carmichael, hence 

 any additional analysis seems unnecessary. 



The specimens received consisted of the mineral in its matrix 

 of cuprite, associated with native copper, cerussite, and a little 

 quartz ; the nantokite was of a pale pea green tint with a slightly 

 effloresced surface; there were also some selected pieces separated 

 from the matrix, from J to J inch through ; at first these possessed 

 but a very pale shade of green, from superficial change, but they 

 gradually became of a darker green and in two or three days the 

 surface effloresced and became opaque and powdery ; when freshly 

 fractured the mineral is practically colourless and transparent and 

 has a highly vitreous or even adamantine lustre. The fracture is 

 small conchoidal, and an occasional obscure cleavage plane is 

 presented. Before the blowpipe it fuses and colours the flame a 

 vivid blue, and on charcoal leaves a globule of copper. I found 

 the specific gravity of these pure fragments to be 4*7 at 27° C, 

 and the hardness 2 '5. 



Although the fragments look like portions of crystals, I could 

 not identify any faces. 



The mineral corresponds in all respects to the description given 

 by Dana (System of Mineralogy, 1892, p. 154) of the original 

 specimens found at Nantoko, Chile. 



G— June 6, 1894. 



