RE-EXAMINATION OF AMERICAN MINERALS. 119 



our opinion is concerned — based on both its chemical and phys- 

 ical character — we unhesitatingly pronounce it an orthoclase. 



Two analyses gave 



1 2 



Silica 64.76 65.17 



Alumina 17.60 17.70 



• Peroxide of iron 50 .50 



Lime 65 .56 



Magnesia 30 .25 



Potash 14.18 13.86 



Soda 1.75 1.64 



Ignition , 65 .65 



100.39 100.33 



These correspond to the composition of orthoclase, and chem- 

 ically the mineral is identical with it; if it shall be proven that 

 the crystalline form is triclinic, it will be a potash albite, and 

 as such an interesting species. 



The specimens examined were received from Messrs. T. F. 

 Seal and William S. Yaux, of Philadelphia. 



12. LOXOCLASE, IDENTICAL WITH ORTHOCLASE. 



The feldspar, associated with pyroxene at Hammond, N. Y., 

 has been named as a distinct species by Breithaupt.* Its crys- 

 talline form, hardness, specific gravity, and other physical 

 characters are the same as orthoclase, and the reasons for 

 forming a new species of it are based upon its cleavage and 

 chemical constitution. The latter Plattner found to be 

 Si 3tl 3Pe Ca Mg Na K H 



63.50 20.29 0.67 3.22 trace 8.76 3.03 1.23=100.70 



We have examined two varieties of it. Analyses 1 and 2 are 

 from specimens taken from a large crystal, and were not per- 

 fectly pure, owing to intimate association with a lime pyroxene; 

 analyses 3 and 4 are from a very pure crystal. 



12 3 4 



Silica 65.40 65.69 66.09 66.31 



£ lumin /"" ™i*\ 20.72 19.15 ( 18 '28 



Peroxide of iron. 1.25] \ .67 



Lime 2.26 2.36 .94 1.09 



Magnesia 20 .25 .21 .30 



Potash 2.76 2.36 4.35 4.35 



Soda 7.23 7.98 7.81 7.81 



Ignition 76 ' .76 .20 .20 



99.34 100.12 98.75 98.96 



* Pogg. Ann., lxvii, 419. 



