130 A. H. Means — New Mineral Occurrences from Utah. 



Index — several crystalline aggregates were matched against a 

 solution having a refractive index of about 1*60. 



The only other bismuth arsenates recorded in Dana are 

 atelestite* and rhagite.f The former occurs very sparingly 

 on bismutoferrite, a bismuth-iron silicate, associated with 

 erythrite, cobalt bloom, at the Neuhilfe mine, Schneeberg, 

 Saxony. The latter is found on bismutite and quartz accom- 

 panied by walpurgite, a basic arsenate of uranium and bismuth, 

 at the Weisser Hirsch mine, Neustadtel, near Schneeberg, 

 Saxony. These, however, occur in but limited amounts and 

 from the description appear to be of interest more as miner- 

 alogical curiosities than for any other reason. 



For purposes of comparison the properties of atelestite, 

 rhagite and the mineral described in this paper are given 

 below : 



Atelestite Rliagite ' New mineral 



Specific gravity. 6*4 6*82 5-70 



Hardness 3-4 - 5 5* ? (about 3 - ) 



Habit monoclinic crystalline crystalline 



aggregates aggregates 



Bi„0 3 83-9 78-8 11-1 



As 2 5 139 15-7 19-3 



H 2 2-2 5-5 3-0 



Color Sulphur- yellowish yellowish 



yellow green green 



The formulas areas follows: Atelestite, 3Bi 2 3 .As„0..2H 2 ; 

 rhagite, 5Bi 2 3 .2As 2 5 .9H 2 0; new mineral, 2Bi 2 3 .As 2 B .2H 2 0. 



Summary.— From the above data it is seen that the material 

 described is homogeneous and of uniform chemical composition. 

 Unlike atelestite and rhagite, which are of sparing occurrence, 

 it occurs in considerable amounts, the material being a con- 

 siderable part of a new stope opened up on the 600-foot level 

 of the Mammoth mine, and assaying 3 to 19 per cent copper, 

 one ounce gold, 150 ounces silver, and 18 to 35 per cent -bis- 

 muth.:}; While it is desirable that additional analyses be made 

 of new material it is nevertheless reasonable to conclude the 

 substance is a definite mineral having a definite composition, 

 which the formula given above approximates very closely, if 

 it does not give it exactly. It is quite possible that a number 

 of bismuth arsenates exist as is the case with copper. 



In view of these facts it seems desirable that the mineral be 

 provided with a name, for which arseno-bismite has been sug- 

 gested as conveying better than any other an idea of its chemi- 

 cal composition. 



Geological Department, Mass. Inst, of Technology, Boston, Mass. 



*Loc. cit., p. 804. fLoc. cit., p. 860. 



X Min. Sci. Press, cix, No. 12, p. 463. 



