Mr. T. S. Hunt's Examinations of some Canadian Minerals. 323 



I. II. ^ ,,v 



Silica .■:;' ,;^'";t 66-44 eew^ -^^^^ 



Alumirir? ''V ^> ^*'-^ 18-35 1 ,„ . ' .' "-^" 



Peroxide of iron . 1-00/ ^^'"^^ '"'''^ 



^'"' •• • • • • '^^ u. , .,;g..aHrp 



Soda 5-56 5-56 :''^ 



Water (losa on ignitio n) •40 ,,.,, , ,.,^1/^^, oijoslloo 

 99-03)'io I rrl" -,"ir/x98?{fa i tii9s sidi 



It is evident from these analyses^ that the composition of the 

 mineral is precisely that of orthoclase^ to which species it had 

 already been provisionally referred by Shepard*, Danaf, and 

 myself J . The proportion of soda is larger than is generally met 

 with in this species; but Domeyko found 4 per cent, of this 

 alkali in an orthoclase from Chili, and Schnederman 10 per 

 cent, in one from Vesuvius, while tkridus othei- sjjefcitilens have 

 afforded 2 and 3 per cent. § ' ' 



The second species to be mentioned is that described by Dr. 

 Thomson under the name of Peristerite||, in allusion to the 

 beautiful play of colours, resembling that of Labradorite^ which 

 it exhibits. 



The specimens furnished me by Dr. Wilson as duplicates of 

 those sent to Dr. Thomson, are composed of a mixture of quartz 

 grains readily distinguishable by their lustre, greater hardness and 

 want of cleavage, disseminated through a felspar, which still so 

 far predominates as to give distinct cleavages to the mass. Spe- 

 cimens furnished me from the same locality exhibited the mineral 

 .in fine cleava.ble masses free from quartz, occasionally passing 

 'into the variety just described. 



' Form triclinic ; the cleavage forms gaveapparentily the angles 

 of those of albite, but did not admit of accurate measurement. 

 Cleavage perfect parallel with P and M, less distinct with T. The 

 surface P shows a fine play of colours like Labradorite, in which 

 a delicate cerulean blue predominates, occasionally passing into 

 light green and yellow. The face M is often marked with striae 

 parallel to P. The same play of colours and striation on alter- 

 nate surfaces are distinguishable in the' masses mixed with 

 quartz. .InO'ui. :. 



Hardness 6. Specific gravity 2-625-2''627. Lustre vitreous, 



* Sec his " .System," &c., p. V,H, 2nd Edition. 



t Diiiiii's Minenil(){,'y, Kd. IHII. p .Sf)!. 



+ .Viniiial llrpoit of Geol. Siirvcv, 1S17-IB, p. l,").'). 



^ See Daiiii, -'^rd Edition, p. 32fi. 



II Phn, Mafr. 1H1.<. .xxii. |). 1«!). 



