40 



Penfield and Stanley — 





I 



II 



Average Batios 



SiO„ 



41-92 



42-06 



41-99 



699 



Tio; 



1-46 







1-46 



018 



A1A 



11-73 



11-51 



11-62 



112 



Fe 2 O s 



2-54 



2-80 



2-67 



017 



FeO 



14-28 



14-36 



14-32 



199 



MnO 



•25 







•25 



003 



MgO 



11-21 



11-13 



11-17 



279 



CaO 



11-50 



11-54 



11-52 



206 



K o 



•92 



1-04 



•98 



010 



Na,0 



2-66 



2-32 



2-49 



040 



H„6 



•66 



•56 



•61 



038 



f; 



•so 







•80 



021 



Loss at 



110° 





•08 







99-96 









= F, 



•33 





Per cents of 

 protoxide bases 



•717 



•129 



Jv'798 



25-0 



•4 

 35-0 ) 

 26-0 



1-2 



5-0 



4-8 



2-6 



60-4 



32-2 



100-0 



99-63 



IX. Horiiblende from Cornwall, Orange Co., .New York.— 

 This is a very black hornblende occurring in masses larger than 

 a walnut and without crystalline outline, imbedded in a rather 

 coarse aggregate of quartz and feldspar. It was originally 

 described by Beck* in 1842 as a new species to which the 

 name Hudsonite was given. It was classed by J. D. Danaf 

 under pyroxene and was analyzed by Brewer;}: and by Smith 

 and Brush. § 



It has recently been reinvestigated by Weidman,|| the 

 material used being a specimen from the Brush Collection No. 

 139, sent to Professor Brush in 1853 by S. R. Horton, who first 

 found the mineral and supplied Beck with specimens for his 

 original description. The prismatic angle m /\ m was meas- 

 ured by Penfield and found to be 55° 31'. The optical proper- 

 ties are described in detail by "Weidman and he also gives a 

 new analysis by J. L. Nelson of the chemical department of 

 the University of Wisconsin. On testing the mineral in a 

 closed tube it was found that the water given off at a high 

 temperature was decidedly acid and accompanied by a deposi- 

 tion of silica, indicating the presence of fluorine, hence it has 

 been possible to make Nelson's analysis more complete by 

 making a determination of fluorine in the material, 0'27 per 

 cent being found. It may also be added that the presence of 

 fluorine in the mineral was suspected because the analysis did 

 not conform to the new ideas concernino; the ratios it should 



* Min. N. Y. 405, 1842. 



% Dana's Mineralogv. 3d ed., 269. 



|| Ibid., xv, 227, 1903. 



f System of Mineralogy, 2d ed., 1844. 

 § This Journal, xvi, 1853. 



