of some Chilian Minerals, 113 



Protoxide of copper . 6*3 



Protoxide of iron . . 3'3 



Alumina . ... 46*3 



Phosphoric acid . . 17*7 



Silica 7'6 



Water 18-8 



100-0 



The presence of so large an amount of silica, and the small 

 percentage of phosphoric acid (but little above one-half that con- 

 tained in the turquoise), at once distinguishes this mineral from 

 the true turquoise for which Dana has given the formula 



2AP0 3 , P0 5 + 5HO*. 



The preceding analysis affords, on calculation, the equivalents 



2CuO, lFeO, 12AP0 3 , 3P0 5 , 2Si0 3 + 26HO, 



and considering the protoxide of iron present to replace a por- 

 tion of the protoxide of copper, will give the following per- 

 centage results : — 



Protoxide of copper . 9*04 



Alumina .... 48*39 



Phosphoric acid . . 16*95 



Silica 7*26 



Water 18*36 



100*00 

 from which the formula 



(CuOFeO) 3 , P0 5 + 2(3A1 2 3 , P0 5 )+2(3A1 2 3 , Si0 3 )+26HO 



may be deduced as representing the constitution of this mineral, 

 making it consequently to be a hydrated compound of tribasic 

 silicate and sulphate of alumina, along with tribasic phosphate 

 of copper. 



Hayesine. — Borate of Lime. 



In a report on the Geology of Bolivia and Southern Peru, 

 made to the Geological Society of Londonf, I attributed the 

 appearance of the borate of lime and other compounds of boracic 

 acid occurring so abundantly in the northern part of the Desert 

 of Atacama and province of Tarapaca in Peru, to the exhala- 

 tions from the numerous volcanoes, whose vapours I supposed 

 (although at that time this had not been proved to be the case 

 in South America) to contain boracic acid ; since then I have, by 



* Mineralogy, 4th edit. p. 405, where, curiously enough, turquoise, 

 although containing 20 per cent, of water, is classed along with the an- 

 hydrous phosphates. 



t Quarterly Journal of the Geological Society, vol. xvii. 

 Phil. Mag. S. 4. Vol. 25. No. 166. Feb. 1863. I 



