S. Weidman — Amphibole Hudsonite. 227 



Aet. XXIY. — Note on the Amphibole Hudsonite previously 

 called a Pyroxene; by S. Weidman. 



Desiring to make a comparison of the microscopic appear- 

 ance of the mineral hudsonite with a certain pyroxene occur- 

 ring in the quartz-syenite of central Wisconsin, the writer 

 requested of and received from Professor S. L. Penfield of 

 Yale University sufficient mineral for this purpose. The 

 material sent the writer is a portion of the specimen* sent from 

 Cornwall, Orange County, ISTew York, to Professor Brush in 

 1853 by S. R. Horton, and which is the same as that sent by 

 the latter to Professor L. C. Beckf about ten years earlier, from 

 which the original description of the mineral hudsonite in 

 1842 was made. 



Thin sections of hudsonite having been made and placed 

 under the microscope, it was seen by the prismatic cleavage of 

 56° and 124° and by the optical properties of low birefring- 

 ence, strong pleochroism and absorption, that this mineral is 

 an amphibole, and not a variety of pyroxene as it has always 

 been supposed. Cleavage fragments of the mineral measured 

 by a hand goniometer also readily showed the prismatic cleav- 

 age to be that of amphibole. Since this mineral has been 

 listed as a member of the pyroxene group for nearly sixty 

 years in all works on mineralogy, it was thought a brief 

 statement concerning its history and character would be of 

 interest. 



History of Hudsonite. — The name hudsonite was proposed 

 by Dr. Louis C. Beck:}: for a new species of mineral, in 1842. 

 The description by Dr. Beck is as follows : " Color, black, 

 often with brownish tarnish. Streak, green. It occurs massive, 

 exhibiting one very perfect cleavage like some varieties of 

 pyroxene. Luster vitreous to resinous. Opaque. Hardness 

 from 4*5 to 5 ; specific gravity 3*5. Alone before the blow- 

 pipe it fuses with effervescence into a black bead, which is 

 attracted by the magnet. This mineral, which is proposed as 

 a new species, was found by Dr. Horton in a vein of quartz in 

 the town of Cornwall, Orange County. Its composition, 

 according to my analysis, is as follows : 



Silica _ 37-90 



Oxide of iron 36 '80 



Alumina _ 12*70 



Lime 11*40 



Magnesia.. . 1*92 



100*72" 



* This Journal, xvi, 369, 1853. 



+ Nat. Hist, of New York, Part III, Mineralogy, p. 405, 1842. 



% Loc. cit. 



Am. Jour. Sci.— Fourth Series, Vol. XV, No. 8*7.— March, 1903. 

 16 



