THE MINERALS OF IDAHO 113 



CINNABAR (66) 



Mercury sulphide, KgS. Trigonal, trapezohedral. 



Cinnabar is the common ore mineral of mercury. It has been 

 noted in small amounts in a number of localities in Idaho and some 

 rather extensive development has been done upon the properties of 

 a few districts. Thus far the ore found has been relatively low grade 

 and large masses of pure cinnabar of even specimen size have rarely 

 been found. The principal localities regarding which definite infor- 

 mation is available are mentioned below. 



BOISE COUNTY 



A heavy concentrate from placer gravels from the Idaho City 

 dredge, Idaho City, contains rare grains of cinnabar associated with 

 samarskite, columbite, and other heavy minerals. No cinnabar has 

 been found in place in this district and the source of the mineral in the 

 placers is not known. Fragments of cinnabar occur in the gravels of 

 the Church placer mine in Marsh Valley and are found in the sluice 

 boxes, used for concentrating the gold. It is said to have been found 

 in place in small seams in the granite of the vicinity. 82 



CASSIA COUNTY 



Cinnabar occurs in claims of the Valentine Cinnabar Co., A l / 2 miles 

 west of Black Pine post office in Cassia County. The deposit is at the 

 top of a limestone bed below shale and was formed by replacement of 

 the limestone. The material is mineralized and friable and is made 

 up mainly of barite and quartz. Tabular crystals of barite project 

 into cavities. The cinnabar forms a very thin sooty or dustlike 

 coating, imparting a red color to the rock but forming only a very 

 low grade ore. The red material contains a little arsenic and is 

 probably a mixture of cinnabar and realgar. Near the surface there 

 is much scorodite in leek green botryoidal fibrous crusts coating the 

 quartz and barite. Some of the cinnabar of this locality seems to be 

 entirely amorphous. The deposit is probably the result of fairly 

 recent hot spring activity. 83 



CLEARWATER COUNTY 



Cinnabar has been noted in placer concentrates from several 

 localities in the Pierce district, although none has been found in 

 place in the region. One coarse sample (Cat. No. 87506, U.S.N.M.) 

 shows grains of massive cinnabar up to 1.5 cm. in diameter in a 

 concentrate from Pierce associated with rutile, corundum, epidote, 

 tourmaline, etc. Another finer sand shows grains of clear red 

 cinnabar with monazite, ilmenite, gold, etc. Pebbles of cinnabar 

 from near Resort are sometimes over 2 cm. in diameter. 



Waldemar Lingren. U. S. Qeol. Survey, Folio 45, 1898. 



Ksper S. Larsen. Univ. of Idaho, Sen. of Mines. Bull. 2, pp. G5-67, 1921. 



