THE MINERALS OP IDAHO 



Angles of arsenopyrite from Ramshorn mine 



139 



Description, quality 



Observed 



Good, very good 55 53 



Good 13 



90 00 

 30 34 



Calculated 



o / 



55 46 I 90 00 

 00 ; 30 47 



In another specimen (Cu 88) from the No. 5 tunnel, Utah Boy 

 Claim, Ramshorn mine, stout prismatic crystals of arsenopyrite of 

 the form shown in Figure 17 occur in vugs in siderite-tetrahedrite 

 ore associated with crystals of siderite and tetrahedrite crystals 

 which are coated with mossy chalcopyrite. The arsenopyrite crystal 

 from this specimen which was measured gave the following forms 

 and angles: 



Forms and angles of Arsenopyrite, Ramshorn mine 



Description, quality 



Observed 



Poor, striated.. 



do 



do 



do 



Excellent 



Fair 



Very poor, dull. 

 Poor, dull 



57 04 



55 48 



56 46 

 55 23 



00 



1 24 



58 



1 34 



90 00 



90 00 



90 00 



90 00 



49 12 



49 12 



32 32 



32 32 



Calculated 



55 46 



55 46 



55 46 



55 46 



00 



00 



00 



00 



90 00 



90 00 



90 00 



90 00 



49 59 



49 59 



30 47 



30 47 



Very minute arsenopyrite crystals also occur included in wall rock 

 fragments inclosed in the vein. 



In the Washington Basin .district arsenopyrite is common in great 

 veins and masses of iron sulphides in the Empire claims of the Idaho 

 Montgomery Mining Co. Specimens show the mineral thickly 

 impregnating greenstone and forming heavy lumps. This arseno- 

 pyrite is massive with no evidence of crystal faces or cleavage and 

 has conchoidal fracture. Where freshly broken it is silver white but 

 it tarnishes iridescent purplish like bornite. When heated in the 

 closed tube the mineral gave the arsenic sulphide and arsenic rings 

 characteristic of arsenop} r rite and reacted abundantly for iron by 

 wet methods. Careful tests for cobalt, nickel, antimony, and copper 

 gave negative results. A specimen from 200 meters (600 feet) south 

 of the north end of the Empire ledge shows gray crystals up to 1 cm. 

 in length and averaging 2 mm. disseminated in quartz. These are 

 gray on fresh fracture, have conchoidal fracture and tarnish purplish. 

 Such material was reported to contain 17 per cent of nickel but the 

 selected arsenopyrite, which is the only metallic mineral, gave no 



