290 REPORT OF NATIONAL MUSEUM, 1899. 



lina do not protrude into Tennessee, except at intervals, and then 

 only for short distances. Some prospecting has been done in Tennes- 

 see near Roan Mountain, but the results were not considered satis- 

 factory.^ 



In Colorado mica has long been known to be widely disseminated 

 and to occur in many places in bodies of workable size, but mining has 

 until lately always proved the mica to be "plumose" and unfit for cut- 

 ting into sheets. Many mines have been located, but the product has 

 always proved worthless, until in the summer of 1884 the Denver Mica 

 Company opened a mine near Turkey Creek, about 35 miles from Den- 

 ver. This mica is of fair quality, and quite a considerable quantity of 

 it has been mined. It is slightly brown and the largest plates which 

 have yet been cut are not more than 2f by (5 inches in size. Only an 

 extremely small percentage of the gross weight is available for cutting 

 into sheets. An effort is being made to put it upon the market, and 

 at present four workmen are employed in trimming the sheets. Mica 

 of good quality and in large plates has also been recently reported 

 from the neighborhood of Fort Collins. 



In Wyoming, mica has been found in workable quantities near Dia- 

 mond Park and in the Wind River country, as well as at many points 

 along the mountain ranges in Laramie County. It has recently been 

 mined to some extent at Whalen canon, 20 miles north of Fort Lara- 

 mie, and some of the product has been shipped to the Eastern market. 



In New Mexico mica occurs near Las Vegas, and reports of ship- 

 ments have been published. At Petaca, the Cribbenville mica mines 

 are being worked at present by sixteen men. Work was commenced 

 at these mines July 2, 1884, and the amount of excavation at present 

 is 13,160 cubic feet. The plates cut range from 2 by 2 inches to 5 by 

 8 inches in size. Some specimen plates have been cut 10 by 12 inches, 

 but the general average is about 3i by tti inches. Some 12 tons of 

 mica have been handled, but the amount sold and .the average price 

 obtained are not reported. Other localities in New Mexico also yield 

 mica, but none have been developed, except the two above mentioned. 

 (Specimen No. 61335, U.S.N.M.). 



In California many deposits of mica have been noted, especially at 

 Gold lake, Plumas county; in Eldorado county; Ivanpah district, San 

 Bernardino county; near Susanville, Lassen county, and at Tehachapi 

 pass, Kern county. In 1883 a large deposit was discovered in the 

 Salmon mountains, in the northwestern part of the State, and some 

 prospecting was done.^ 



The mica-bearing deposits of the Black Hills of South Dakota ht've 

 been variously regarded by different observers as intrusive granites 

 or true segregation veins lying parallel to the apparent bedding. New- 



^ Mineral Resources of the United States, 1887, p. 671. 

 ^ Idem, 1883-84, p. 911, 



