ae a the northeast side of the fault. The structure on the northeast side cf the fault is less woll lnovm. A second fault, called the "centre fault", striking approximately cast and dipping 50 degrees to the south, is exposed on the 300- and 400-foot levels of the mine, from 100 to 200 feet northeast of the “south fault". The trace of the “centro fault" has not been found on the surface, 4 third main favlt, called the "Yorth fault", -is exposed near the base of the northeast side of the "mine hill", about 3800 feet northeast of the “south fault". It trends northwesterly and is marked by a breeciated zone 50 foet or more wide, Two north-south branch faults were ohserved on the south face of the “mine hill". Other branch faults occur underground. The faults described above are all part of the Pinchi fault zone, the northeastern border of which forms tho Permian~ Jurassic contact. : F Economie Gcolegy Cinnabar is the only mineral kmown to occur in economic quantity in tho mino. It is concentrated in the breeciated zones along the faults as well as in the strata cut by the faults. The ore-bodies occur mainly in dolomitized limestone in the vpper levels of the mine, and in quartz-mica-carbonate schists in the lower levels. The limestone contains solution cavities that range in size from mere pits to openings several fect across. Many of these cavities are largoly filled with caleitee In the upper part ef the mine much of the cinnabar is in these solution cavities. In the lower part most of the cinnabar occurs along fractures in highly shattered schists, Throughout the mine good ore is found in the fault breccias. One-half mile southeast of the main mine workings an ore- body occurs in a carbonatized and brecciated zone cutting a small body of serpentine. Most of the cinnabar at the mine fills premoxisting openings in the host rocks such as fissures, solution cavitics, and interstices, and other factors being equal, it is apparent that the grade of the ore increases in direct ratio to the number of openings. However, there has been some replacement of the wall-rocks, especially limestone. The known ore-bodies roughly parallel the bedding, They strike approximately northe= west and dip to the northeast’ at about 50 to 60 degrees. They are limited along their dip by the northwesterly trending, southwesterly dipping faults. The other boundaries are gradational end appear to depend on assay values only. The upper ore-body outcrops along the crest of the "nine hill". It is limited down its dip by the "south fault", which dips southwesterly. The middle ore-bodies occur between the "south and centre faults", and the lower ore-bodies north of the"centre fault", The middle and lower ore=bodics do not outcrop at the surface. The: ecinnabar occurs as veinlets, blebs, and individual grains, and mostly as the:massive red, variety. Some bright rod, earthy cimnabar oceurs in the upper part of the Pinchi Lake merevry imine, and erystallized cinnabar in the lower part. "A little stibnite has been found in associa- . . tion with some very rich ore in the upper part of tho deposit. Scattered grains of pyrite are found throughout the mine. The common gangue minerals are quartz and calcite,’ Most of the quartz is fine-grainsd, but a few crystals were observed in open cavities. The, quarts anc: chnnabar were deposited contemporaneously. The calcite formed before and after the cinnabar, In some specimens cinnabar may be’ scen filling imterstices between calcite crystals and as coatings on the crystals. In other speci- mons cimabar and caleite fill cavities in which it is quite evident that calcite was deposited first, then cirmabar and quartz, and finally calcite again. Alunite occurs in the mineralized limestones, A few specks of barite were obsorved associated with the mercury deposit in the serpentine.