SUMMIIDKS, VKSKNIDKS, ANTI MI >M I )| - :jl)7 



small basal plane. It is isomorphous with wurtzite, the fibroin 

 zinc sulphide ; used in t tie spintharoscope to demonstrate the radia- 

 tions of radium. 



It occurs in the Joplin region of Missouri as a yellow coating on 

 crystals of calcite and sphalerite. The yellow smithsonite of 

 Arkansas, or " turkey-fat ore," owes its color to an admixture of 

 grrenockite ; it also occurs in small quantities with zinc minerals 

 at l-'riedensville, Pennsylvania, and as a furnace product. 



Artificial crystals of greenockite have been obtained by fusing 

 cadmium sulphide, sulphur, and potassium carbonate, or from a hot 

 solution of cadmium sulphide in ammonium sulphydrate, which 

 deposits crystals of greenockite on cooling. 



MILLERITE 



Millerite. Capillary pyrite ; Hair sulphide ; NiS, sulphide 

 of nickel ; Ni = 64.6, S = 35.3 ; Hexagonal ; Type, Ditrig- 

 onal Polar (?), c = .9883 ; 0001 A 1121 = 48 46'; H. = 3-3.5 ; 

 ( 1 . = 5.3-5.65 ; Color, bronze-yellow ; Streak, greenish black ; 

 Luster, metallic. 



B.B. On coal in the O. F. blackens, fuses to a globule, and 

 yields a sulphur dioxide odor. Well roasted, the black oxide- 

 reacts for nickel with the fluxes ; it may contain iron, cobalt, or 

 copper, all of which will interfere with the bead reactions. 



General description. In very slender elongated crystals or 

 hairlike tufts, often interwoven and matted, as at Antwerp, New 

 York, where it occurs in cavities of hematite. It often forms 

 botryoidal crusts with a radiated structure, as at the Gap mine, 

 Lancaster County, Pennsylvania; here it is associated with a 

 granular pyrrhotite. Very fine tufts of the hairlike variety are 

 found in cavities of calcite and dolomite near St. Louis, Missouri. 



Nickel, as is shown by the analyses of rocks made by the United 

 States Geological Survey, is a very common constituent of igneous 

 rocks, though as a very minor accessory mineral, amounting to .027 

 per cent. It is to the concentration of this trace of nickel that the 

 occurrence of millerite in veins and cavities is due. 



Beryrichite, Ni 3 S 4 , and polydymite, Ni 4 S 5 are rare, though they 

 may be formed under nearly the same conditions as millerite. 



Millerite, from its restricted occurrence, though rich in nickel, is 

 of minor importance as a nickel ore. 



