THE MANZANITA. 367 



tion several feet in thickness and in part as narrow seams of rich ore. One 

 observer describes the deposit as a replacement vein between serpentine 

 and sandstone. The vein matter is decomposed country rock and the 

 gangue is quartz. The strike of the deposit is nearly north and soutli.' 



Colusa County mines. — Ouc of the most interesting deposits in the world is 

 the Manzanita mine, on Sulphur Creek, close to the hot sulphur springs 

 now known as Wilbur Springs, but formerly as Simmons's Springs. The 

 rocks are highly metamorphosed beds of the Knoxville series. At a dis- 

 tance of about three-quarters of a mile from the mine is a bed of limestone, 

 composed of .shells oi Rhyndionella Whitiieyi, held together by a small amount 

 of matrix. Within a few yards of the mine itself I collected perfectly re- 

 cognizable specimens of Aucclla concentrica. The age of the rocks is thus 

 fully determined. The strata are thin-bedded, highly altered and con- 

 torted, shaly sandstones, a part of them somewhat serpentinized. The 

 waters of the hot springs, which are only a few hundred feet from the mine, 

 are highly charged with sulphureted hydrogen and are very salt. They 

 also seem to contain borax. The surrounding country shows that, as is so 

 usual with springs of this class, the position of the vents has repeatedly 

 changed and much of the rock in the neighborhood has been leached by 

 sul}>huric acid. Hot sulphur waters once issued from the mine itself, for 

 it contains a large amount of free sulphur. The ore consists of cinnabar 

 and gold, which are sometimes in direct contact, and some metacinnabarite. 

 These minerals are accompanied by pyrite and marcasite, chalcopyrite, 

 stibnite, calcite, and quartz. The gold is often visible in feather-like, crys- 

 talline aggregates, sometimes in direct contact with cinnabar and some- 

 times deposited directly upon calcite, which is more prevalent in the ore 

 than is quartz. The cinnabar and gold are often separated by a layer of 

 calcite an eighth of an inch in thickness. Oily and resinous bitumens are 

 also tolerably abundant in the workings. 



The ores and gangue minerals do not form a regular deposit, but occur 

 as thin seams, penetrating the rock sometimes along the partings between 

 strata and sometimes cutting across the beds. It is evident on inspection 



'This iu form, at ion is derived from an unpublished report of Mr. C. A. Luckhardt, Report of tbe 

 Miuing Commissioners, 1876, and from Statistics and Technology of the Precious Metals, by Emmons 

 and Becker. 



