466 Hidden and Pratt — Associated Minerals of Rhodolite. 



In the above analysis the ratios only approximate to the 

 generally accepted formula, II 2 . 4(Mg. Fe)G . 4A1 2 3 . 10SiO 2 , 

 and it is undoubtedly due to a slight admixture of some 

 hydrated iolite with the material analyzed. 



Cyanite, tremolite, fibrolifce (?), hornblende, rutile and menac- 

 canite occur, but of a too common order to merit any extended 

 mention in this paper. 



Staurolite. — This mineral has a rich garnet red color and is 

 perfectly transparent; being apparently free from its cus- 

 tomary inclusions. Its specific gravity is 3*80. 



Only small fragments and rounded masses of the staurolite 

 have been found and these were often mistaken by the miners 

 for the pyrope garnet. 



Monazite and Zircon. — These two species occur abundantly 

 as minute crystals and grains in the finer and heavier concen- 

 trates. They rarely exhibit well-defined crystalline forms but 

 are usually perfectly transparent and very brilliant. 



A few rough crystals of monazite were found that were 

 decidedly green in color and were from 2-6 mm thick in the 

 direction of the o axis. This green color would seem to indi- 

 cate the isomorphous replacement of Th0 2 by U0 2 similar to 

 the occurrence in the green xenotime of Brindletown, N. C* 

 Cyrtolite. — Gentlrf has mentioned the occurrence in this 

 valley of "peculiar dark brown crystals from l-3 mm in size 

 which may be zircon." What are probably the same kind of 

 crystals have been found in the concentrates with the rhodolite, 

 but only two of these were saved. The exterior of the crys- 

 tals is black or very dark brown, while the interior of one is a 

 yellowish brown. The specific gravity is 3*71. 



One of the crystals measured 6 mm in the 

 direction of the c axis. Orienting the crystals 

 according to zircon, the only forms observed 

 were the prism of the second order a, 100 and 

 the unit pyramid of the first order p, 111, 

 which were identified by means of the contact 

 goniometer, giving p^p f = 56° 30', while for 

 zircon p ^p' = 56° 40' 26". The crystals were 

 smooth and developed as represented in fig. 1, 

 neither of them being doubly terminated. 

 No analysis has as yet been made of these 

 crystals, but they are undoubtedly hydrated alteration products 

 and should be classified with the so-called malacon and cyrto- 

 lite group. 



Gold. — A small sample of slightly impure gold was finally 

 saved, after much labor of re washing the concentrates and 



*L. G. Eakins, this Journal, June. 1892. 



f Bulletin U. S. Geol. Survey, No. 74, 1891, p. 49. 



