442 



SCIENCE 



[N. S. Vol. XLIX. No. 1271 



production of several carloads of ore contain- 

 ing about 3 per cent. IJ3O5. 



The discovery was made quite by accident 

 by Mr. Eoss Lambert, of Casper, Wyoming. 

 Having purchased some land near Lusk, with- 

 out any reference to its mineral value, Mr. 

 Lambert found on the ore dximps of a former 

 silver mine which had been abandoned more 

 than thirty years ago a mineral that at- 

 tracted his attention by its peculiar yellowish- 

 green color. Mr. Lambert had a complete 

 analysis made of some picked specimens by 

 Mr. W. L. Piers, of Denver, who reported 

 among other things a content of uranixmi 

 corresponding to more than 20 per cent, of 

 U3O,. 



In September, 1918, one of the writers had 

 the privilege of visiting the deposit which is 

 situated at Lusk, Wyo., on the Chicago and 

 Northwestern Eailway, about twenty miles 

 from the eastern boimdary of Wyoming, near 

 the ISTebraska-South Dakota intersection. Al- 

 though considerable prospecting has been done 

 in the region since Mr. Lambert's discovery, 

 the uranium ore so far appears to be confined 

 to a single hill about one quarter of a mile in 

 circiunference at its base and tapering up to 

 a sharp conical top about 350 feet above the 

 base. The hill was known by the Indians as 

 Silver Cliff HiU, and still caixies this name. 

 It is about one half mile north of Lusk, and 

 lies at the extreme eastern edge of the Hart- 

 ville uplift. The uranium occurs entirely in 

 quartzite which lies between mica schist and 

 granite. The ore is marked by its extreme 

 variations in appearance. The most typical 

 variety is a greenish-yellow very intimately 

 mixed with quartzite having well rounded 

 grains resembling tapioca in structure and 

 color. However, the predominance of other 

 oxides can conlpletely alter the color and ap- 

 pearance of the ore without the uranium con- 

 tent being affected. Por example, a variety 

 containing iron oxide has a rich chocolate- 

 brown color, and yet contains 12 to 15 per 

 cent. UgOg in some cases. Predominance of 

 greenish shades is due to the presence of 

 copper carbonates. Other specimens are 

 black with a glassy lustre, owing to a very 



intimate mixture of a small quantity of 

 iiraninite in the quartzite. In the absence of 

 coloring by these extraneous oxides, the min- 

 eral approaches a canary yellow, resembling 

 that of camotite. In some cases, the colors 

 are found absolutely different in a single piece 

 of quartzite without its chemical composition 

 or the uranium content differing in the va- 

 rious zones. This is due to the high color- 

 ing power of a slight predominance of one or 

 the other oxides. A very small proportion of 

 uraninite in the quartzite can color it almost 

 a jet black. 



It has been very difBcult to obtain pure 

 crystals of the uranium mineral itself suit- 

 able for purposes of identification. However, 

 Drs. F. B. Laney and E. D. Larsen, of the 

 U. S. Geological Survey have been kind 

 enough to examine some specimens collected 

 by one of the writers. Dr. Larson's measure- 

 ments of the optical properties indicate 

 very decidedly that the mineral is identical 

 with uranophane, a hydrated calcium silicate 

 containing some barium and lead, to which 

 the formula CaO(ir03)„(SiOJ3.6H20 has 

 usually been assigned. It is readily soluble 

 in acids. The chemical evidence of the 

 writers does not show correspondence with 

 this chemical formula, but further work, both 

 chemical and optical, is desirable before more 

 definite statements can be made about the 

 crystal form or chemical composition. Dr. 

 Laney's microphotographs of polished sections 

 indicate that the uraninite in the quartzite 

 was introduced subsequent to the deposition 

 of the sandstone and replaced the cementing 

 material, and to a less extent, the sand grains 

 themselves. Dr. Laney believes the mineral is 

 probably an oxidation product of uraninite 

 (U3O,). 



The chemical evidence of the writers on 

 material not so pure as could be desired 

 (about 80 per cent, pure) indicates that the 

 soluble bases and acids account for each other 

 without reference to the m-anium oxide at all. 

 This was taken to indicate the existence of a 

 free higher oxide, probably UO3. Since the 

 occurrence of this oxide in nature has not 

 been reported, if confirmed, it would con- 



