120 
SOME REMARKABLE HOT SPRINGS AND ASSO- 
CIATED MINERAL DEPOSITS IN COLUSA 
COUINTW,, CAILIUEORUNIUA, 
BY HAROLD W. FAIRBANKS, BERKELEY, CALIFORNIA. 
A Group of remarkable mineral springs occurs in the 
valley of Sulphur Creek, Colusa County, on the eastern 
slope of the Coast Ranges. This section is formed of 
Cretaceous shales and sandstones, which to the west, in 
the higher portion of the range, are replaced by an older 
basement series. 
The Coast Ranges, judged from the standpoint of their 
economic minerals, are characterized particularly by the 
presence of large deposits of cinnibar. A little to the west 
of the locality about to be described the cinnibar deposits 
are seen clearly to be closely related to volcanic phenome- 
na. Mineral springs of every description are more abundant 
than in any other portion of California. Lava of late 
Tertiary age covers much of the country in the vicinity of 
Clear Lake and southward, and it is probable that the 
springs date from the close of the volcanic activities. 
The famed Sulphur Bank at the eastern end of Clear 
Lake, where has been mined for many years both cinnibar 
and sulphur, is perhaps the best known of the interesting 
phenomena in this volcanic region. Almost unknown, 
however, is the group of remarkable hot springs and 
resultant deposits of gold and cinnabar in the Sulphur 
Creek Mining District. Here gold and cinnabar have 
been deposited from the same. solfataric vent, but, 
what is the most remarkable, both in commercial quan- 
tities. While in most mineral regions, as far as our 
observations have gone, the deposition of minerals has 
almost if not quite ceased, here it is still going on, and 
the most excellent opportunities are presented for the 
study of such phenomena. 
It must not be supposed that the gold deposits of 
Sulphur Creek are typical of the others of the State, for, 
indeed, they are not. . This is the only locality, as far as 
I am aware, in which gold is found in veins in Cretaceous 
rocks in California. As a statement of general applica- 
tion it may be said that the epoch of the formation of 
quartz veins, and the associated gold deposits, ceased 
before the deposition of the lowest cretaceous beds; that 
is, following the great upheaval at the close of the Jurassic. 
» Only locally is there apparent any metamorphism in the 
Cretaceous. ‘lhe epoch of the cinnibar deposits is very 
much later, probably beginning at the close of the great 
volcanic activities following the Miocene, and in rare 
instances, as in the case under discussion, continuing up to 
the present time. 
About the town of Sulpher Creek is a group of quick- 
silver mines, several of which show deposits of the usual 
character, that is, cinnibar distributed in irregular vein 
form in a gangue of silicified serpentine. The Manzanita 
mine lies on the north side of the creek, and it is here 
that the gold and cinnibar are associated in such an 
interesting manner. ‘They occur in various places over a 
hill about half a mile in diameter, and which rises several 
hundred feet from the valley. It is evident that at some 
past time the whole hill has been thoroughly permeated 
by hot mineral waters, and either simultaneously or at 
different epochs, gold deposits were formed from silicious 
waters in certain spots, while in others cinnibar with more 
basic solutions almost changed the character of the 
original shales and sandstones. Cinnibar in small quan- 
tities, and often associated with sulphur, can be found 
over’ a large portion of the hill. The distinctly gold 
quartz veins occur on the western side, where great cham- 
bers have been excavated in following the veins. Here 
are thin seams of black quartz, with which calcite is often 
= SCiHaNCE: 
Vol. XXIII. No. 578 
associated, frozen to the hard silicified walls (originally 
shale). It is apparent that the quartz was formed in 
open cavities, not only from the fact that it is always 
found firmly attached to the walls, but also that open 
spaces still remain through the centres of many of the 
veins. These spaces are lined with beautiful drusy crys- 
tals of quartz and are sometimes a foot across. The 
chambers have been worked out down to the water-line, 
where the gold was found to be largely contained in tron 
pyrites. In the outer portion of these quartz veins much 
bitumen is often found, while the centre is sometimes 
filled with soft white magnesian and aluminous material. 
The Manzanita mine was first located for quicksilver 
but was subsequently worked for gold. In 1891 prepara- 
tions were being made to save both the gold and the 
quicksilver, which in many places are found together. At 
the foot of the hill on the east, where the original works 
were located, a hot spring still exists. In one of the 
older workings near this spot beautiful examples of 
gold and cinnibar in the same hand specimen were 
obtained. The hot waters were finally encountered, and 
work in that direction had to cease. An examination of 
the whole hill shows a remarkable variation in the 
occurrence of gold and quicksilver with sulphur and 
bitumen. 
The Monticeto mine lies on the south side of the creek 
just above the town. Gold has been found here in two 
sandstone strata a little distance apart and inclosed in 
shale. The sandstone stands vertical, while the gold 
occurs in thin horizontal seams of a loose sandy character. 
The adjoining shales are considerably silicified. The 
largest sandstone stratum has a width of ten feet and has 
been mined out for some distance on the ore shoot, which 
_dips at an angle of 30°. 
The most interesting of all the mines about Sulphur 
Creek is the Elgin, situated three miles up the valley 
from the village. Hot springs, still flowing a large 
amount of water and highly mineralized, issue from a 
very steep bluff on the south of the creek. Over much of 
an area, several. hundred feet in extent, the formation 
consisting originally of argillaceous rocks and sandstone, 
and possibly some serpentine, has been almost completely 
replaced by silicious and calcareous sinter. The mine is 
opened by two tunnels, the lower one nearly four hundred 
feet above the base of the hill, and the upper less than a 
hundred feet higher up. The lower tunnel has been run 
in about one hundred and eighty feet with branches and 
cross-cuts. As one enters, heated air, saturated with 
moisture and sulphurous vapors, is at once encountered, 
and all surplus clothing is dispensed with. When well 
within the tunnel the air grows hotter and more stifling, 
but one is well repaid by the sights which open to his 
gaze, and by the feeling that he is witnessing nature at 
work in her laboratory in a manner which is seldom open 
to man. The hill seems to have been fissured in every 
direction. Through these fissures poured mineral waters, 
once much more abundant than at present, partly or 
completely filling the cavities and largely replacing their 
walls by silicious and calcareous deposits. The tunnel 
seems almost lined with beautifully banded aragonite mixed 
with silicious sinter of different kinds, varying in color 
from black to white, and in texture from porous to com- 
pact. Much of it is almost glassy and opalescent. Dis- 
tinctly crystallized silica or quartz is rare. Here and 
there great cavities stretch away and downward farther 
than one can see, being completely lined with sparkling 
crystals of calcite, or stalictitic forms often grouped and 
branching like huge corals. One mass was observed 
nearly two feet in diameter, quite spherical, and entirely 
surrounded by radial stalactites four to five inches long. 
At the limit of one of the workings water of almost boiling 
