344 



BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



green chlorite and feldspar with long blades of cyanite and some 

 biotite. Embedded in the feldspar are black needles of tourmaline 

 up to 1 cm. in length. One of these which was measured was ter- 

 minated and of the habit shown in Figure 108. This gave the fol- 

 lowing angles: 



Measurements of tourmaline, Avery Quadrangle 



WASHINGTON COUNTY 



In the Jessie mine, 3^ mile northwest of Mineral, in the Mineral 

 district, a vein 2 to 3 feet wide consists of pyrite and chalcopyrite 

 in a gangue of quartz and tourmaline. The vein is inclosed in diorite 

 and carries some gold. 67 



STAUROLITE (428) 



Orthorhombic. 



Basic iron-aluminium silicate, approxi- 

 mately 2Fe0.5Al 2 3 .4Si0 2 .H 2 0. 



The only locality thus far known for staurolite in Idaho is in the 

 southern part of the St. Joe Basin and along the St. Joe Clearwater 

 divide as described below. 



SHOSHONE COUNTY 



Staurolite is strikingly developed in some of the metamorphosed 

 rocks of the Belt series in the southern part of the Avery quadrangle 

 in southern Shoshone County. The crystals, which reach an extreme 

 length of 10 cm. are either twinned and cruciform or are simple and 

 well-developed prisms. Typical specimens showing the larger 

 twinned crystals from this locality are illustrated in Plate 9. The 

 mineral is practically confined to a uniform bluish banded slate which 

 has been determined by F. C. Calkins as representing the upper 

 Wallace formation. 



The crystals of staurolite are usually fresh and unaltered and have 

 the usual brown color. 



A specimen from just north of the 6,320 -foot summit between 

 Bathtub Mountain and Junction Peak (Avery quadrangle, southeast 

 corner) contains numerous large brown untwinned staurolite crystals 

 up to 2 by 4 cm. in size associated with a few small pink garnets in a 

 fine micaceous base. Another specimen from the west side the knob 



« Waldemar Lindgren. U. S. Geol. Survey, 22 Ann. Rept., pt. 2, p. 755, 1901. 



