ART. r,i MINERALS FROM SOUTHERN" UTAH — SHANNON 5 



was replaced by the oxide ot" a heavy bivalent metal, lead, and the 

 mineral was named plumbojarosite. In the hand specimen these two 

 new members of the group had the same appearance as ordinary 

 jarosite, from which they can not be distinguished without chemical 

 tests, although the lead member may be recognized by its higher 

 specific gravity in some specimens. Numerous examples appear to 

 exist isomorphousl}^ intermediate between the plumbojarosite, natro- 

 jarosite, and jarosite. Plumbojarosite carries sufficient lead to have 

 been smelted in several instances as an ore. Utahite, vegasite, and 

 several other supposedly distinct species have been found to be 

 identical with one or the other of the above minerals. 



Still more recently a jarosite mineral very rich in silver from the 

 Tintic district in Utah has been examined by Schaller ^ and found 

 to have silver oxide as the essential base in place of potash. To this 

 interesting mineral, the first known in which silver enters as an 

 oxygen compound, the name argentojarosite was given. This, again, 

 had superficially all of the characteristics of ordinary jarosite. Since 

 such unexpected cases of isomorphism in this group it is hard to 

 predict what others may be found. In the Boss mine in Nevada a 

 small amount of plumbojarosite was mined which carried compara- 

 tively large amounts of platinum and palladium.^ These apparently 

 were not entirely present as the native metals and the platinum and 

 palladium may have replaced the lead of the plumbojarosite. The 

 jarosites are essentially minerals of arid climate. Although occur- 

 ring in numerous localities where sulpliides have oxidized in dry 

 regions, the minerals of the group are almost unknown in areas of 

 more humid climate. 



Erickson ^ described jarosite occurring associated with the tscher- 

 migite from Wyoming as coating or sometimes inclosed in the alum 

 and also in pure nodular masses. It was pale yellow in color and fine 

 grained, but the individual crystals could be recognized under the 

 highest magnifying power of the petrographic microscope. Since an 

 ammonia member of the jarosite group was anticipated the ammonia 

 content of this "Wyoming material was determined and found to be 

 1.30 per cent (NPIJ.O, or 1.25 per cent when corrected for included 

 tschermigite. Although an ammoniacal variety, this obviously did 

 not closeh' approach the ammonia end member of the group. With 

 Erickson's results in mind, the prqsent writer veiy carefully exam- 

 ined the jarosite associated with the Utah tschermigite and upon 

 analysis this w^as found to contain a definite preponderance of am- 



' Waldcrmar T. Schaller. ArsrentojarositP, a new silver mineral. Preliminary note. 

 Jouru. Wash. Acad. Sci., vol. 13, No. 11, p. :.'33, 1023. 



* Adolph Knopf. A gold-platinum palladium lode in southern Nevada. U. S. Geol. 

 Survey Bull. 020, pp. 1-18, 1016. 



• E. Theodore Erickson. Journ. Wash. Acad. Sci., vol. 12, pp. 40-54, 1022. 



