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414 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 41. 



and gentle slopes at its base and about 500 feet above the railroad 

 at Lucin, Four claims have been located, and these are, in order 

 from northwest to southeast, Utah Gem, Greenback Lode, Utahlite, 

 and Protection Lode. The variscite deposits are in and around small 

 rocky summits standing above the rest of the hill. These summits 

 have cavities and small caverns in them, resembling those made by 

 wave action. They were probably formed on one of the shore lines 

 of the former Lake Bonneville. The work done at the time of exam- 

 ination consisted of an open cut 50 feet long and 2 to 5 feet deep, 

 with several prospect pits. 



The rock in wliich the variscite occurs and wliich forms the crest 

 of the hill is cherty or chalcedonic quartz which contains inclusions 

 of nodules and streaks of limestone. The limestone inclusions range 

 up to a foot tliick and in places are several feet long. The character 

 of most of the rock is that of a hard breccia cemented together by 

 sihca. This breccia forms rough rocky ledges and knobs rising from 

 a few feet to 25 feet above the hill slopes. Three of these knobs 

 contain large quantities of variscite. 



The variscite occurs in balls, nodules, and irregular masses in the 

 chert. Veins of variscite are not common, but some with a northeast 

 strike and northwest dip were seen on the Utah Gem claim. The 

 nodules and balls of variscite range in size from a fraction of an inch to 

 several inches across, and some of the segregations of variscite inclos- 

 ing matrix are a foot across. The variscite fills fractured and brec- 

 ciated zones in the rock, some of wliich it replaces and some of which 

 it incloses. The replacements are generally rounded concretionary 

 masses, often with a banded concentric structure. The fragments of 

 some of the brecciated rock, especially wliite quartz, that have been 

 inclosed by and cemented with variscite have remained angular and 

 sharp. Some of the concretionary forms appear to grade from green 

 variscite cores into the inclosing yellow, brown, gray, and wliite phos- 

 phatic and cherty minerals. There is considerable chalky mineral filling 

 cavities in the variscite-bearing rock and coating the nodules and 

 masses of variscite. A quantity of variscite pebbles and cobbles have 

 been found in the open cut in the loose detritus below the main out- 

 crop on the Utahlite claim. These pebbles probably owe their 

 rounded form largely to the nodular shape of the variscite in the 

 original rock, but also probably to some extent to water action on a 

 former lake shore. The pebbles are coated with a wliite chalky sub- 

 stance, and have to be broken into before the presence or quaUty of 

 the variscite can be determined. 



Both the variscite and the matrix minerals possess various shades 

 of color, several of which are sometimes present in a single specimen. 

 The different colors combined with the various markings and patterns 

 due to the structure of the mineral and brecciation of the matrix 



