NO. 2345 



CONTRIBUTIONS TO MINERALOGY— SHANNON. 



443 



The specimen is from an unstudied collection of ores, made by 

 Edward L. Jones, Jr., formerly of the United States Geological 

 Survey. The writer is indebted to Dr. F. L. Kansome for freely 

 consenting to the present use of the material. 



CRYSTALLIZED TETRAHEDRITE FROM THE HYPOTHEEK MINE, PINE 

 CREEK DISTRICT, IDAHO. 



Tetrahedrite occurs commonly in the Hypotheek mine in the Pine 

 Creek district of Idaho in a portion of the vein which is barren of 

 galena, and contains, in addition to the tetrahedrite, chalcopyrite, 

 pyrite, and arsenopyrite in a gangue of quartz, calcite, and siderite.^ 

 Tetrahedrite is very rare in this district, although it occurs com- 

 monly in veins of a different type in the adjoining Coeur d'Alene 

 district. In this general region the tetrahedrite is usually massive 

 and more or less highly argentiferous. The specimens from the 



Fig. 11.— Ckystal of tetrahedeite. 



Fig 12.— Crystal of tetrahedeite. 



Hypotheek mine examined by the writer are those collected by Jones, 

 and they are labeled as coming from the old workings east of the 

 fault on the 700-foot level. 



The specimens consist of coarse vitreous white vein quartz contain- 

 ing the greasy appearing gray tetrahedrite filling narrow veins. 

 Small open cracks in the quartz are lined with minute quartz crys- 

 tals and well-bounded crystals of tetrahedrite which reach five milli- 

 meters in diameter. Most of these show bright faces, which yield ex- 

 cellent reflections of the signal. The development is such, however, 

 that the tetrahedral symmetry is not apparent. A typically de- 

 veloped crystal is shown in figure 11. The most completely de- 

 veloped and synunetrical crystal measured is shown in somewhat 

 idealized form as figure 12. The forms recognized are o{lll), 

 n{211),d{110), andr(332). 



» Jones, E. L. Jr. A Reconnaissance of the Pine Creek Dristriet, Idaho, Bull. U. S. 

 Geo!. Surv. No. 710-A. p. 27. 



