Chemical Composition of 

Naturally Occurring Fluids 

in Relation to

Mercury Deposits in Part of 

North-Central California

GEOLOGICAL SURVEY BULLETIN 1382-A

Chemical Composition of 

Naturally Occurring Fluids 

in Relation to

Mercury Deposits in Part of 

North-Central California

By IVAN BARNES, M. E. HINKLE, J. B. RAPP, CHRIS HEROPOULOS, 

and W. W. VAUGHN

CONTRIBUTIONS TO ECONOMIC GEOLOGY

GEOLOGICAL SURVEY BULLETIN 1382-A

A report of the chemical composition of waters, 

gases, hydrocarbons, sulfur, and rocks 

associated with mercury deposits

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1973
UNITED STATES DEPARTMENT OF THE INTERIOR 

ROGERS C. B. MORTON, Secretary

GEOLOGICAL SURVEY 

V. E. McKelvey, Director

Library of Congress catalog-card No. 73-600015

For sale by the Superintendent of Documents, U.S. Government Printing Office

Washington, D.C. 20402 Price 45c domestic postpaid or 30c GPO Bookstore

Stock Number 2401-00296
CONTENTS

Page

Abstract........................................................................................................ ....... Al

Introduction............................................................................................................ 1

Acknowledgments ..................... ... ........................................................ 4

Methods ............................................................................................................ 4

Geology.................................................................................................................... 5

Results of chemical analyses................ ........................................................... 11

Results of gas analyses... ............................................................................. 13

Minor Element analyses....................................................................................... 14

References.... .................................................................................................... 17

ILLUSTRATION

Page

FIGURE 1. Sample sites........-..............-.........-.................... .................... A3

TABLES

Page

TABLE 1. Geology of sample sites............................ .... .. . ... .... A6

2. Composition of ground water and steam condensates................. 10

3. Results of analyses of gases................................ .. ... 14

4. Mercury content of samples....... . ........................................ 15

5. Approximate concentrations of mercury species in waters at

equilibrium with red cinnabar.................................................... 16

6. Mercury content of solids found in sampling localities... .. 16

ill

CONTRIBUTIONS TO ECONOMIC GEOLOGY

CHEMICAL COMPOSITION OF NATURALLY

OCCURRING FLUIDS IN RELATION TO

MERCURY DEPOSITS IN PART OF

NORTH-CENTRAL CALIFORNIA

By IVAN BARNES, M. E. HINKLE, J. B. RAPP, 

CHRIS HEROPOULOS, and W. W. VAUGHN

ABSTRACT

The composition of fluids in the area studied displays a regional trend from 

chloride-rich waters east of the Stony Creek fault to bicarbonate-rich waters 

west of the fault although each fluid source must be regarded as a special 

case because of the local complexities of geology. Within the area studied are 

many mercury deposits. Although many examples were found of fluids presently causing silica-carbonate alteration, the usual wallrock alteration in 

mercury mines, none of the fluids sampled seem capable of forming commercial mercury deposits. The mercury concentrations in waters are all less than 

the acceptable limit for the mercury concentration of drinking water.

INTRODUCTION

The Coast Ranges of California have long been recognized as 

a favorable area for studying fluid-solid interactions in a wide 

variety of geologic processes. Early work, notably that of Waring 

(1915), described unusual fluids. Later work by White (1957) 

brought order out of seeming chaos. Studies of regional geology, 

especially those of Irwin (1960) and of Bailey, Irwin, and Jones 

(1964), provided a general geologic setting for subsequent work.

This report considers analyses of samples from 20 sites in 

Glenn, Colusa, Lake, and Sonoma Counties, north-central California. Materials sampled were ground water, steam condensates, 

tarry petroleum, and dissolved gases; analyses were made to determine major and minor constituents, including mercury. Although 

the complexity of the geochemical relations is obvious, some general comparisons and specific features of the fluid composition in 

relation to geology will be made. The trend from chloride-rich 

ground water east of the Stony Creek fault to chloride-bicarbonate rich water on the fault and to bicarbonate-rich water west of

Al
A2 CONTRIBUTIONS TO ECONOMIC GEOLOGY

the fault is also striking. The detailed geology of each locality, 

however, shows each fluid source to be a special case. Sampling 

locations in the homoclinal, structurally simple clastic marine 

sedimentary rocks of the Great Valley sequence of rocks of the 

Sacramento River valley serve as a reference. These fluids and 

rocks are not particularly unusual and serve as a basis for comparison with the more exotic fluids issuing from the structurally 

complex Stony Creek fault. The fluids from the Great Valley 

sequence also contrast with the very unusual fluids issuing from 

the structurally chaotic Franciscan terrane.

The location of sampling sites is shown in figure 1. Also shown 

in figure 1 is the surficial expression of the easternmost traces of 

the Coast Range fault (Bailey and others, 1970) and the Stony 

Creek fault (Brown, 1964, Rich, 1971). The Coast Range fault 

is usually expressed (Bailey and others, 1970) as, from west to 

east (structurally upward), Franciscan rocks in fault contact 

with the lower (ultramafic) part of an ophiolite sequence overlain by sedimentary rocks of the Great Valley sequence. The easternmost trace of the Stony Creek fault, between the ultramafic 

rocks and overlying Great Valley sequence, is a major geochemical boundary separating the Great Valley geochemical province 

to the east from the Coastal geochemical province to the west 

(fig. 1). The chemical composition of the waters from depth in 

the Great Valley geochemical province is characterized by high 

chloride to bicarbonate proportions. Along the trace of the Stony 

Creek fault, shown in figure 1, the waters are usually of a mixed 

chloride-bicarbonate type. West of the Stony Creek fault the 

waters are rich in bicarbonate. Locally the Franciscan rocks 

which lie west of the Coast Range fault are in structurally discontinuous blocks, poorly exposed and often mantled by landslide 

debris. Metamorphic grades may be irregularly distributed. In 

spite of the complex geologic relations west of the trace of the 

Coast Range fault shown in figure 1, virtually all the waters of 

the Coastal geochemical province are characterized by high bicarbonate to chloride proportions.

Extensive mercury production has taken place in the area 

studied (White, 1967), but most of the production has been from 

the Coastal geochemical province west of the eastern limit of the 

Stony Creek fault. Sulphur Bank (White and Roberson, 1962), 

the Western Mayacmas district (Bailey, 1946), the Eastern 

Mayacmas district (Yates and Hilpert, 1946), the Wilbur Springs 

district (Moiseyev, 1968), and the Skaggs Springs mercury mine 

(Everhart, 1950) are important examples.

Many of the mercury mines both in the area studied and else-
NATURAL FLUIDS, MERCURY DEPOSITS, CALIFORNIA A3

HUMBOLDT COUNTY] TRINITY COUNTY

TEHAMA COUNTY

EXPLANATION

Sampling site and 

number. See list

Fault 

Dotted where concealed

Thrust fault 

Dotted where concealed. 

Sawteeth on upper plate

MENDOCINO COUNTY

GLENN COUNTY

( COASTAL

IGEOCHEMICAL 'l 

\ PROVINCE

/

GEOCHEMICAL

y \

SONOMA COUNTY 

.21

NAPA COUNTY

38°

123°

10 20 30 50 MILES

No. Site

1 Salt spring north of 

Sites

2 Wilbur oil test well

3 Salt spring north of 

Wilbur Springs

4 Salt Spring

5 Sulphur Spring

6 Wilbur Springs

No. Site 

1 Spring east of Alice 

mine

8 Deadshot Spring

9 Complexion Spring

10 Fouts Redeye Spring

11 Abbott mine

12 Grizzly Spring

13 Seigler Springs

No. Site

14 Sulphur Bank well

15 Castle Rock Spring

16 Adit near Anderson 

Spring

17 McKinley steam field

18 Alien Spring

20 Bartlett Springs

21 Skaggs Springs

FIGURE 1. Sample sites.

where are in silica-carbonate rock, which is an alteration product 

of serpentinite (Bailey and Everhart, 1964) in the Coastal geochemical province. Many of the mercury mines discharge bicarbonate-rich solutions that are shown (Barnes and others, 1973)
A4 CONTRIBUTIONS TO ECONOMIC GEOLOGY

to alter serpentinite to silica-carbonate rock. The association, of 

the fluids appropriate to yield silica-carbonate rock with economic 

mercury deposits led to the reasonable hypothesis that the bicarbonate-rich fluids may be related to the ore-forming fluid. As a 

consequence the fluids in the area were analyzed for their mercury 

concentrations in addition to an extensive suite of other major 

and minor elements.

ACKNOWLEDGMENTS

We thank Mr. Frederic D. Hanson for permission to sample 

in the Abbott mine, Turkey Run Tunnel, and we thank the Signal 

Oil Co. for permission to sample the McKinley steam-field condensates and well cuttings. Donald E. White collaborated in the 

fieldwork.

METHODS

Gases were collected in plastic syringes by displacement of the 

native water, and the syringes were carried to the laboratory 

immersed in a bottle of the native water. Gas analysis was by gas 

chromatography with helium as the carrier gas. A 6-foot by 

i/i-inch aluminum column of Porapak Q1 (150-200 mesh) was 

used at temperatures between 22° and 26 °C and flow rates 

between 50 and 56 cc per min (cubic centimeters per minute) to 

determine hydrogen, methane, ethane, and carbon dioxide. A 

3-foot by i/i-inch aluminum column of Linde molecular sieve 13X 

was used at temperatures between 23° and 29 °C and flow rates 

between 27 and 36 cc per min to determine hydrogen, oxygen, 

nitrogen, carbon monoxide, and methane. Steam condensates were 

obtained by condensing the steam in aluminum tubing immersed 

in a tank containing ice and water. The aluminum tubing did not 

accumulate a detectible amount of mercury. The condensate 

emerged at temperatures of 0°C to 2°C. Water samples were collected in 4-liter plastic bottles. Some samples were filtered through 

0.45^ (micrometer) pore size ethyl acetate filters in a stainless 

steel pressure reservoir and stainless steel filter holder using nitrogen in high-pressure cylinders as a pressure source. A part of the 

filtered water was acidified to pH 2 with concentrated hydrochloric acid for analyses of calcium, magnesium, ammonium, aluminum, and iron. Another part of the filtered water was left 

untreated for analyses of silica, sodium, potassium, sulfate, chloride, fluoride, bromide, iodide, boron, and specific conductance. 

Bicarbonate and pH were determined at the sampling site by the

^The use of brand names in this report does not constitute endorsement by the U.S. Geological Survey. Equivalent products can be used for the processes.
NATURAL FLUIDS, MERCURY DEPOSITS, CALIFORNIA A5

methods of Barnes (1964). Analytical procedures generally were 

those described by Brown, Skougstad, and Fishman (1970). The 

hydrogen sulfide content of condensate from the McKinley steamfield wells was determined in the laboratory and may be of questionable validity. Aluminum was determined by atomic absorption 

spectrophotometry, with 1,000 mg/1 (milligrams per liter) potassium added to samples and standards.

Samples for mercury analysis were acidified to pH 1 with concentrated hydrochloric acid and analyzed by the procedure of 

Hinkle and Learned (1969). Water samples were filtered by 

suction through 0.45^ cellulose acetate filters.

Chemical precipitates from springs were analyzed for mercury 

by the mercury detector technique of Vaughn and McCarthy 

(1964). Sulfur interference in the precipitate samples was overcome by heating the samples and collecting the evolved mercury 

on a cool gold gauze, allowing the hydrogen sulfide to pass through 

the gold collector. The gold gauze was then heated to allow the 

mercury to pass into the detector.

Petroleum and tarry residues were analyzed for mercury both 

by an oxygen bomb procedure (Hinkle, 1971) and by a dithizone 

colorimetric procedure following acid digestion of the sample 

(Ward and McHugh, 1964) ; analytical results from both procedures showed good agreement.

Identification of solid phases were by X-ray diffraction and 

optical methods. Calcium-magnesium carbonate compositions were 

determined by determining the unit cell dimensions by leastsquares refinement (Barnes and O'Neil, 1971).

GEOLOGY

The geologic relations are fairly simple in concept in a broad 

sense, with the Coast Range fault separating Great Valley sequence rocks from Franciscan rocks. Local relations, however, 

may not fit the larger relations, and the structural complexity of 

the Franciscan rocks may result in chaotic local geologic relations. 

The geochemical relations may be fully as complex.

Detailed descriptions of geologic materials found at the springs 

or wells are given in table 1. Some of the more important relations at the sampling sites are given in the following text, in the 

same sequence as in table 1. The sample localities are listed insofar 

as possible in a structural sequence. The sequence is from the 

Great Valley geochemical province farthest northeast of the Stony 

Creek fault to the Coastal geochemical province farthest southwest of the northeastern trace of the Stony Creek fault.
A6 CONTRIBUTIONS TO ECONOMIC GEOLOGY

CO

CO

 S",

CO

5u 

Os

0

sS1

rH

H

03

H

U A

OCX

C O BO

£ 50.2

o u o

"S * J> «S M

Si

-lit

<U B

 a*

 3 *^^

B'^" <u

si

^I'i

w esX

<u c o

60£ O «<2"

o

« .2

5|* 

0"! fr*B 

U

 i 00 23 

It

x^i

jj «

W a

05

BD

Litholo

||

§(§

u

55

 J

e

1

C,

"3

u

i

41

1

bt

41

a

>

"a

5

"9

a

.*

41

£

u

c

o

co

£

<M

o

I

41

U

V

9

»

^

w

75 

~a

i*

U

c

8

^

s c. S;

_ j- ^,

|2 -5

05 2

in 

n

£

s

Z

**-< ""^ .- -.IM""

3 i *I-H »« > §W^ 

O ri.C'^/ *^n u

t> *^ ^ J3 (M^J*^*-*^

w ^H^MN o.^^ ^^ 

O D

|1

is ** **

H

s f.s

«|.|S.2u-n

 « i 3 -^2

£

 g-o u <u

« C C J5 

^ es O 3 *O *2 U *i 

0 o to C to

 §|| 2-p

^ *^

w Cfl

of JT;

ro . . ^ . 

«oo 2 "^ 2 

-rt ^ o ^-^"^ o

OT Z

S

*

i«

hfl**-< - 

.5 ° 'o""

6

OJ

ao

In

%

__ ^ o 2^

1 'Jo M 5*0 

- « l. 3 jj

1 3^8§ '

! Si © c v*

P O. u r*^ O C H ao us

 i ^

||

"S S'3

O

6'BON"

l|ti _

2 aO u--c

|loll

O

o

eg

CO ^

§| 

^ 0

cd ^

u

01

J2«

V)

eo

c'C

&0u^ ^

_C O w

u c

i-sas,

giS S-S

O 41 

^ C

& a *5>
NATURAL FLUIDS, MERCURY DEPOSITS, CALIFORNIA A7

 ooC - 

522 ~

U T3 U

O.£ <u O 0.0 w n

^roroOnOOO

C I* 0!

,« o > 

hos eig it

H 'S 3 S"'S !? uv!< o£ii ?. '9'r'X^frr f \^m -^ * H\ I ** Ul O

5^X °?-S8

.S <u

E5 5*- oo

Q

3c rt o S « SeSoCS O®'S S

Vg x g-p S

3-c«2 grtSS & aOSM COOOQ. 55

°2'-g B ^2 |S «

, u ^ a»E» o

;a

C<

compos Cao.eM

j-.S 0 0 00

u o

> o-|G

'v Q 6

=iii

gortg 

;5.2 "es'SS £ ou

n .

!^l

Cfl

O BO 

£ C

ti

Q

Erl

05?
A8 CONTRIBUTIONS TO ECONOMIC GEOLOGY

J3

' 4J

C 

o

o

e?

OCX

C O CD

£U2 

o u o

l-a 05 O

?l§

Miner 

ssemb

S .

&3E

gas fc aio«

 o S O O g

'g'S_

 *j

-

.S Q. ^ w I-1 *^ O.

o t: u bt3 <u 8? 

c o"o E xS^

u « c = E

c^'c -5«

-So. NJS
NATURAL FLUIDS, MERCURY DEPOSITS, CALIFORNIA A9

1 province)

u

1

1

"a

a 

e 

0

u

e

"3

 a"3

I 

o

VI

o

2

u

V)

NO

w

m

Mesozoic............

CO

1

£

albite, Quartz, orthoclase, kaolin, and muscovite.

Valley real 

sequence.

O

Soi

a

V)

on

c«
A10 CONTRIBUTIONS TO ECONOMIC GEOLOGY

The salt spring north of Sites, Calif., issues from the Salt Lake 

fault (Brown and Rich, 1961). Wilbur oil test well and the salt 

spring north of Wilbur Springs issue from the eastward dipping 

homoclinal sequence of Great Valley rocks east of the Coast Range 

fault (Rich, 1971).

Many of the waters issuing from the Stony Creek fault are 

described as issuing from serpentinite or its equivalents. The 

ultramafic rocks are structurally beneath the ophiolite sequence 

according to Bailey, Blake, and Jones (1970). Where the fluids 

issue from the fault, part of the fluids may be from the Great 

Valley sequence and part may be from the Franciscan rocks.

The occurrence of rodingite in the cataclastic graywacke found 

in Salt Valley has structural significance. As Barnes and O'Neil 

(1969) and Barnes and others (1973) showed, rodingites are 

formed during episodes of serpentinization. The ultramafic body 

was in part still fresh when placed in contact with the graywacke 

and underwent serpentinization later as the serpentinizing fluid 

flowed across the contact into the graywacke.

Complexion Spring issues from lizardite-chrysotile serpentinite 

and deposits brucite and a magnesia-silica gel (Luce, 1971) ; it 

appears to be affected by serpentinization by the criteria of 

Barnes and O'Neil (1969).

TABLE 2. Composition of ground

[Minerals stated in milligrams

Sample Si02 Al Fe Ca Mg Na

1Locality no longer accessible. Analysis from White, Hem, and Waring (1963). 

2Data from U.S. Geol. Survey flies, C. E. Roberson, analyst.

NH4

Salt spring north of Sites.......

Wilbur oil test well...................

Salt spring north of Wilbur

Springs.....................................

Salt Spring, Salt Valley..........

Sulfur Spring, Salt Valley......

Wilbur Springs..........................

Spring east of Alice mine.......

Deadshot Spring.. ......................

Complexion Spring....................

Pouts Redeye Spring................

Seigler hot spring.......................

Seigler lukewarm spring

(The Geyser) ..........................

Abbott mercury mine1..............

Grizzly Spring2...........................

Anderson Spring adit...............

McKinley steam well 1..............

McKinley steam well 3..............

Castle Rock Spring...................

Sulphur Bank well....................

Alien Spring................................

Bartlett Springs.........................

Skaggs spring 1. ........................

Skaggs spring 2.........................

Skaggs Springs well..................

.. 17

.5

.. 130

... 140

... 54

... 200

... 95

... 120

... 24

... 125

... 170

... 160

... 116

.. 56

.. 50

... 8

.2

... 125

... 140

... 44

... 100

... 133

... 127

... 77

0.4

.29

.3

.51

.26

.2

<0.1

.1

<0.1

<0.1

.66

.33

1.6

.3

.1

<0.02

.08

.1

.32

.54

0.4

<0.02

6.2

.13

.16

.04

.04

2.1

.06

2.5

.22

.60

.0

.1

3.7

.12

.05

<0.02

.38

<0.02

<0.02

8,850

580

490

115

48

2.8

8.8

160

.7

104

30

21

64

135

78

1.1

.3

14

19

78

67

13

14

19

79

92

228

262

68

38

300

345

.8

254

238

140

443

712

34

.1

.05

1.9

40

162

286

4.6

4.7

5.8

9,500

6,700

4,600

8,400

890

8,500

860

2,000

12,000

3,800

162

212

1,500

2,720

28

1.9

.1

64

1,310

24

10

955

930

1,060

40

55

255

90

15

440

84

164

350

56

20

40

39

53

6.6

.1

<0.1

3.2

41

1.6

.8

31

31

42

18

17

135

155

20

280

34

105

210

30

12

10

22

1.7

11.5

86

107

.5

490

.1

.14

2.0

2.2

2.6
NATURAL FLUIDS, MERCURY DEPOSITS, CALIFORNIA All

Castle Rock Spring and the McKinley steam-field fluids issue 

from a melange of Franciscan rocks. Graywacke, greenstone, 

chert, and serpentine are all represented in cuttings from McKinley well 1. Less than a mile north of the steam field is Lincoln 

Rock, a block of isolated blueschist in a landslide. The serpentinite 

found at shallow depth contains cinnabar in calcite veins. Kaolin 

is the alteration product of the albite in the graywacke of the 

steam-producing zone.

Skaggs Springs issue from rocks of the Coastal belt of Irwin 

(1960). Coastal belt rocks share many of the features of both 

Franciscan and Great Valley sequence rocks and may be regarded 

as intermediate between the Franciscan and Great Valley sequence rocks. It is not surprising that the fluids should be similar 

to the fluids issuing from the contact between Franciscan rocks 

and Great Valley sequence rocks.

RESULTS OF CHEMICAL ANALYSES

The results of analyses for major elements are given in table 2. 

Regional variations in water compositions are discernible but are 

complicated by the regional geologic relations. Both the Salt 

Spring north of Sites and the Wilbur oil test well are northeast 

of the eastern limit of the surficial expression of the Stony Creek

water and steam condensates

per liter. NA, not available]

HC03

21

62

2,040

3,150

866

7,130

1,840

3,280

7.1

5,000

1,320

900

2,710

4,490

233

206

303

192

2,090

1,010

1,640

2,450

2,440

2,880

COS

0.02

2

2

39

.9

6

41

7

889

30

1.2

1.5

.1

.04

.05

2

16

.4

.5

SO4

130

72

31

63

54

390

5.8

6

60

7.0

6.3

7.2

467

4.8

283

133

36.3

24.4

1,630

17.5

2.2

6

3

5

Cl

30,900

11,400

8,300

11,800

1,210

9,700

1,240

3,140

18,200

3,990

272

297

1,900

3,940

3.0

10

23

6

782

26

4.4

56

57

60

F

0.6

.4

.7

1.4

.1

2.5

<C0.1

.5

.5

1.1

<0.1

<0.1

1.0

.3

<0.1

<0.1

.6

.8

<0.1

<0.1

10

10

10

Br

160

41

33

45

16

7

9

70

22

2

2

3.8

13

<0.1

<0.1

<0.1

6

<0.1

<0.1

I

70

34

23

50

27

3.3

8

50

6

.7

.5

6.3

12

<0.1

<0.1

<0.1

<0.11

<0.1

<0.1

Specific 

ConducB H2S tance pH 

(mmhos/cm 

at25°C)

17

23

250

200 NA

17 12

310 190

40

110

20 3

115

19

17

56 <1

178

.11

.45 3

<0.01 11

.72

620 NA

.44 ......

.08 ......

85

91

97

64,700

28,200

23,800

32,300

4,770

33,000

5,890

12,300

47,300

16,000

2,530

2,160

8,960

14,700

860

556

715

356

7,880

1,440

2,080

3,430

3,430

3,960

6.89

8.60

7.04

8.11

7.18

6.87

8.40

7.31

12.07

7.88

6.88

7.22

7.1

7.2

6.74

6.48

6.37

8.14

7.95

6.77

6.61

6.87

6.92

6.72

Temp.

18

21

22

19

22

55

18

18

9.5

15

50

44

26

18

41.5

>100

>100

53.5

85

13

17

55

54

24
A12 CONTRIBUTIONS TO ECONOMIC GEOLOGY

fault and show the high chloride: bicarbonate ratio commonly 

found in waters issuing from Great Valley sequence rocks. The 

chloride-rich waters are connate as defined by White (1965).

The salt spring north of Wilbur Springs and the Salt Spring 

in Salt Valley, Wilbur Springs, the spring east of the Alice mine, 

Deadshot Spring, Fouts Redeye Spring, the Abbott mine, and 

Grizzly Spring are on or very close to the Stony Creek fault, and 

the water analyses show subequal concentrations of chloride and 

bicarbonate. The fluids are considered in part connate modified 

by metamorphic reactions (White, 1957; Barnes, 1970).

Complexion Spring has an unusually high pH. In spite of the 

marked difference in chemical composition between Complexion 

Spring and the calcium hydroxide type waters probably resulting 

from present-day serpentinization (Barnes and O'Neil, 1969), 

the reaction state with respect to olivine, pyroxenes, brucite, and 

serpentine is the same for Complexion Spring water as for the 

calcium hydroxide type water. In spite of the high pH due to 

reactions with enstatite and forsterite and of the Mesozoic age of 

the source rocks, the sodium, potassium, chloride, bromide, and 

fluoride of Complexion Spring are remarkably close to the concentrations found in present-day ocean water, although the youngest 

rocks exposed are Cretaceous (Rich, 1971). As is characteristic 

of the moderately saline waters of California, ammonia and iodide 

are high, presumably because of decay of marine organisms.

The Seigler Springs are both much richer in bicarbonate than 

in chloride. Whether the chloride content is contributed by the 

surrounding Great Valley sequence rocks (Swe and Dickinson, 

1970) or whether both the bicarbonate and the chloride are from 

the presumably underlying Franciscan rocks is not known. The 

steam condensates from the McKinley steam wells and water from 

the Anderson and Castle Rock Springs are entirely from Franciscan rocks and have anomalously high bicarbonate for local meteoric 

water from Franciscan rocks. The steam is dry that is, it does 

not entrain liquid water; nonvolatile cations are therefore quite 

low. The sulfate is in large part from the oxidation of hydrogen 

sulfide subsequent to sample collection. Later field analyses by 

L. Willey from a different steam well show more than 100 mg/1 

hydrogen sulfide in the freshly collected steam condensate. The 

chloride of the steam condensates is higher in concentration than 

that of the spring waters. Possibly this relation indicates loss of 

some of the undissociated hydrogen chloride (HC1°) from depth 

rather than the evaporation of chloride-containing water because 

of very low values of cations other than ammonia. The slower 

natural upflow yields lower chloride because of dissociation of
NATURAL FLUIDS, MERCURY DEPOSITS, CALIFORNIA A13

HC1° at lower temperatures. The volatile constituents carbon 

dioxide, hydrogen sulfide, and ammonia are also lower, probably 

owing to condensation in the upper part of the vapor-dominated 

system (White and others, 1971).

Alien Spring and especially Bartlett Springs show extreme 

examples of fluids from the Franciscan rocks. Bartlett Springs 

are inferred to discharge locally derived meteoric water on the 

basis of sodium, potassium, ammonia, sulfate, chloride, fluoride, 

bromide, iodide, and boron concentrations and ratios. To the 

locally derived meteoric water has been added carbon dioxide 

from the presumably underlying Franciscan rocks. The carbondioxide-rich water alters serpentine to silica carbonate rock, 

removing magnesium, calcium, iron, and silica (Barnes and 

others, 1973). The iron in solution in both Bartlett and Anderson 

Springs is below detection because the discharges are so slow 

that the iron is entirely precipitated, as shown by the copious 

sludge of ferric hydroxide in the spring orifices.

The Skaggs Springs and well issue fluids from coastal-belt 

rocks. The coastal-belt rocks are intermediate in character (Irwin, 

1960) between Franciscan and Great Valley sequence rocks. Certainly, the chloride is higher than in Bartlett Springs but not as 

high as in waters on the Coast Range fault.

RESULTS OF GAS ANALYSES

The results of gas analyses are given in table 3. Not all the 

springs discharge gases. A rough indication of atmospheric contamination is the oxygen content of the gases as analyzed. Nitrogen contents are partly atmospheric, but nitrogen is also a 

component of gases issuing from depth as distinct from air 

(Rudkin, 1968, p. 123). Hydrocarbon gases are produced in large 

quantity from Great Valley sequence rocks. The gas issuing from 

the salt spring north of Sites is an example of the hydrocarbon 

gases from the Great Valley sequence rocks. Along the easternmost expression of the Stony Creek fault are found gases rich in 

carbon dioxide (salt spring north of Wilbur Springs) or rich in 

methane (Salt Spring in Salt Valley). More common are carbondioxide-rich gases such as issue from Wilbur, Deadshot, Fouts 

Redeye, Grizzly, and Seigler Springs and the Sulphur Bank well. 

The hydrogen in the discharges of the wells is released from the 

water during oxidation of well casing and may constitute a major 

fraction of the gases discharged. Different gas compositions are 

found in adjacent wells and from the same well at different times 

(table 3). In spite of the fact that the McKinley steam wells are 

entirely in Franciscan rocks, there is a large methane component,
A14 CONTRIBUTIONS TO ECONOMIC GEOLOGY

TABLE 3. Results (in volume percent) of analyses of gases

Salt spring north

Salt spring north

Salt Spring, Salt Valley.. 

Wilbur Springs. ....... ........

Fouts Redeye Spring...... 

Grizzly Spring..................

Seigler lukewarm spring 

Sulphur Bank well... ...... ..

McKinley 1 steam well, 

17 March 70..................

McKinley 1 steam well, 

24 March 70..................

McKinley 3 steam well, 

17 March 70..................

McKinley 3 steam well, 

24 March 70..................

Skaggs spring 1..............

Skaggs spring 2..............

Skaggs Springs well.. ......

02

0 Q

.4

1.9

4

2.1 

.3

1,8

1.6 

B.9

5

.1

1.3

.7

1.2

9 1

1.7

N2

5.8

.9

9.2

1.0

2.5 

.8

2.3

4.6 

16

2.5

3.4

6.0

6.6

4.4

K I

13

CH4

94

2.0

57

7

1.9

.06 

1.0

3.0

15 

24

5.7

7.9

8.3

14

28

91

52

CO2

0.2

98

32 

93

95

92

97

92

79 

59

38

31

28

10

69

76

38

Other

H2=1.6

H2=50

Ho=60

H2 -60

Ho=73

C2HG=0.26

CoHc=0.13

especially after correcting for dissolved air and hydrogen from 

well-casing reactions. Methane may also be the major component 

in the gases discharged from coastal-belt rocks.

The results of the gas analyses show regional trends. It is safe 

to say that the highest methane: carbon dioxide ratios are found 

in gases from the Great Valley section. It is also safe to say that 

the highest carbon dioxide:methane ratios are found from the 

Stony Creek fault westward but that methane may be the dominant component in some places. The proportions of carbon dioxide 

to methane cannot be explained in detail because the relative 

amounts in deeper reservoirs are unknown. The rates of gas flow 

are complicated by the relative solubilities (carbon dioxide is 10 

times as soluble as methane in water) and also by the fact that 

carbon dioxide may hydrolyze and further react.

MINOR ELEMENT ANALYSES

As noted in the introduction, the fluids studied include the 

carbon-dioxide-rich fluids that may cause the silica-carbonate 

alteration of serpentinite. The silica-carbonate rock is commonly 

the host rock of mercury deposits in California. Samples were 

analyzed for mercury, and the results are given in table 4. In 

spite of their close association with mercury deposits and, even 

more surprising, the fact that they include some that cause the 

usual wall-rock alteration, the fluids studied are low in mercury. 

Even the analyzed condensate of the dry steam from wells is 

quite low, although cinnabar has been found in cuttings from the
NATURAL FLUIDS, MERCURY DEPOSITS, CALIFORNIA A15 

TABLE 4. Me,rcury content of samples

[nd, not detected] 

Sample Hg (u.g/1)

Wilbur oil test well, unfiltered. . ............................................. 0.2

Salt spring north of Wilbur Springs, unfiltered ....................... .1

Salt Spring, Salt Valley, unfiltered................................................ nd

Sulfur Spring, Salt Valley, unfiltered............................................ nd

Wilbur Springs, unfiltered ............................................................. 1.5

Spring east of Alice mine, unfiltered............................................ nd

Deadshot Spring, unfiltered........................................................... nd

Complexion Spring, unfiltered........................................................ 1.5

filtered....................................................................................... .1

Fouts Redeye Spring, unfiltered ....................................... .... . nd

Seigler hot spring, unfiltered.......................................................... nd

Seigler lukewarm spring, unfiltered .................... .................. nd

Abbott mine water, unfiltered.......................................................... 1.0

filtered... . ......................................._..................... . .. nd

Grizzly Spring, unfiltered ...................................................... .. nd

Anderson Spring adit, unfiltered ................................................. nd

McKinley steam well 1, variable condensation temperature,

unfiltered ................................................................................ .5

variable condensation temperature, filtered... . . .2

condensed to 0°C, unfiltered................................ ................. 3.0

condensed to 0°C, filtered.......................................................... nd

McKinley steam well 3, variable condensation temperature,

unfiltered ................................................................................ .9

variable condensation temperature, filtered...... .. . .7

condensed to 0°C, unfiltered ................................................. 1.0

condensed to 0°C, filtered........................................................ .1

Castle Rock Spring, unfiltered........................................................ nd

filtered............................................................................................ nd

Sulphur Bank well, unfiltered............................................... ... .. 1.5

filtered.............. ....................................................................... .5

Alien Spring, unfiltered ................................................................. nd

Bartlett Springs, unfiltered........................................................... nd

Skaggs spring 1, filtered ......... .. . .................... .09

algal material (dry weight). . ..... .. . IXlO4

sediment (dry weight).............................................................. 4xl04

Skaggs spring 3, filtered........ ..................... ............................... .07

Skaggs Springs well, filtered.......................................................... <.05

algal material (dry weight).................................................... 2

sediment (dry weight)................ .... .... ... .... .08

Little Warm Springs Creek above Skaggs Springs, filtered...... <.05

filtered...-......-.-.----...-...-..-.....--.....-..........- .... .05

one well examined petrographically. All materials analyzed contained less than 5 /*g/l (micrograms per liter), the maximum 

considered safe for drinking water by the U.S. Public Health 

Service.

Evidently, most mercury in the economic deposits of the area 

studied was not transported by fluids like those analyzed. The silica 

in water yielded by graywacke and greenstone is 20 to 50 mg/1 but 

is much higher in carbon-dioxide-rich water from silica-carbonate 

rock or serpentinite. Silica and magnesium are being leached 

from serpentinites to form silica-carbonate rock (Barnes and 

others, 1973). Even if 10 mg/1 silicate is leached from the silicacarbonate rock, the 1 /*g/l of mercury available for precipitation 

has at most 0.01 percent the volume of rock being leached. The
A16 CONTRIBUTIONS TO ECONOMIC GEOLOGY

continued discharge of the fluids studied will leach rocks rather 

than form economic deposits.

In spite of the low mercury concentrations, most of the waters 

that contain both mercury and hydrogen sulfide are supersaturated with respect to both black (metacinnabar) and red (cinnabar). The solubility data of Barnes, Romberger, and Stemprok 

(1967) and the composition of Wilbur Springs with its remarkably high concentration of 190 mg/1 of total sulfide sulfur and 

near neutrality (table 2) indicate that equilibrium concentrations 

of mercury species may be calculated. In table 5 are given solubilities of red cinnabar in Wilbur Springs water and in water with 

10 mg/1 hydrogen sulfide and 10 mg/1 bisulfide. Wilbur Springs 

water is apparently at equilibrium with red cinnabar; the mercury content may be due to leaching of cinnabar. The other 

mercury concentrations found are greatly supersaturated with 

cinnabar; hence, the mercury cannot be ascribed to a leaching 

process.

TABLE 5. Approximate concentrations (in fig/I) of mercury species in waters at equilibrium with red cinnabar

Dissolved Temperature (°C) 

Species 20 100 

Wilbur Springs

HgS (HoS) 2---..----..-.---------- 0.1 2

Hg (HS) 3-1 -------------------- -2

HgS (HS) 2-2 --..---------.------- .4

Water with 10 mg/1 HgS and 10 mg/1 HS 

HgS (H2 S) .............................................................10-3 lO-2

HgS (HS) 2-2 ...-----..-----.-.-.-----10-3

The mercury in solution is deposited in the immediate proximity of the springs. Algal material, sediment, hydrocarbons, sulfur 

from the oxidation of hydrogen sulfide in Wilbur Springs, and 

rocks contain relatively high concentrations of mercury (table 6).

TABLE 6. Mercury contents (in parts per million) of 

solids found in sampling localities

Mercury

Hydrocarbon (tarry) from the Abbott mine............ 500

Hydrocarbon (heavy oil) from the Wilbur oil test 

well.................................................................................. 1

Fault gouge, Abbott mine........ ...................................... 1-5

Sulfur from surface of Wilbur Springs........... ........... 30

The complete removal of mercury near the springs is demonstrated by the relatively low (near or below detection limits) 

mercury contents in sediments and algae a few meters downstream from spring orifices. The mercury enrichment then is 

quite localized and does not constitute a dispersed mercury enrichment of concern to human health. Although there are local mercury enrichments, the fluids do not constitute sources of economic
NATURAL FLUIDS, MERCURY DEPOSITS, CALIFORNIA A17

mercury deposits because of the relatively large amount of rock 

the waters can dissolve for the volume of mercury that can precipitate.

Various calculations can be made on rates of deposition of 

mercury in economic deposits. Calculated using the 50-gpm discharge of Sulphur Bank reported by White and Roberson (1962) 

and a mercury content of 1 /*g/l, the deposition of the Sulphur 

Bank ore would have required 40 million years, or from the 

Eocene to the present. However, much of the ore is deposited in 

Holocene rocks (White and Roberson, 1962). Our findings are in 

complete agreement with those of White and Roberson (1962) 

that the fluids presently discharging from Sulphur Bank cannot 

have formed the mercury deposit.

As far as we can determine, the deposition of mercury ores of 

economic grade is episodic. The deposition episode has ended in 

the area studied, although the fluids still issuing may cause the 

rock alteration now found. Perhaps continued detailed studies in 

the Coastal geochemical province will find a current depositional 

site to further our understanding of the geochemistry of mercury.

REFERENCES

Anderson, C. A., 1936, Volcanic history of the Clear Lake area, California: 

Geol. Soc. America Bull., v. 47, p. 629-644.

Bailey, E. H., 1946, Quicksilver deposits of the western Mayacmas district, 

Sonoma County, California: California Jour. Mines and Geology, v. 42, 

no. 1, p. 199-230.

Bailey, E. H., Blake, M. C., Jr., and Jones, D. L., 1970, On-land Mesozoic 

oceanic crust in California Coast Ranges, in Geological Survey Research 

1970: U.S. Geol. Survey Prof. Paper 700-C, p. C70-C81.

Bailey, E. H., and Everhart, D. L., 1964, Geology and quicksilver deposits of 

the New Almaden district, Santa Clara County, California: U.S. Geol. 

Survey Prof. Paper 360, 206 p.

Bailey, E. H., Irwin, W. P., and Jones, D. L., 1964, Franciscan and related 

rocks, and their significance in the geology of Western California: California Div. Mines and Geology Bull. 183, 177 p.

Barnes, H. L., Romberger, S. B., and Stemprok, M., 1967, Ore solution geochemistry II. Solubility of HgS sulfide solutions: Econ. Geology, v. 62, 

p. 957-982.

Barnes, Ivan, 1964, Field measurement of alkalinity and pH: U.S. Geol. Survey Water-Supply Paper 1535-H, 17 p.

 1970, Metamorphic waters from the Pacific Tectonic Belt of the West 

Coast of the United States: Science, v. 168, p. 973-975.

Barnes, Ivan, and O'Neil, J.R., 1969, The relationship between fluids in some 

fresh alpine-type ultramafics and possible modern serpentinization, Western United States: Geol. Soc. America Bull., v. 80, p. 1947-1960.

 1971, Calcium-magnesium carbonate solid solutions from Holocene 

conglomerate cements and travertines in the Coast Range of California: 

Geochim. et Cosmochim. Acta, v. 35, p. 699-718.
A18 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Barnes, Ivan, O'Neil, J. R., Rapp, J. B., and White, D. E., 1973, Silica-carbonate alteration of serpentine Wallrock alteration in mercury deposits 

of the California Coast Ranges: Econ. Geology (in press).

Barnes, Ivan, Rapp, J. B., O'Neil, J. R., Sheppard, R. A., and Gude III, A. J., 

1972, Metamorphic assemblages and the direction of flow of metamorphic 

fluids in four instances of serpentinization: Beitr. Mineralogie u. Petrologie, v. 35, p. 263-276.

Brice, J. C., 1953, Geology of Lower Lake quadrangle, California: California 

Div. Mines and Geology Bull. 166, 72 p.

Brown, R. D., Jr., 1964, Geologic map of the Stonyford quadrangle, Glenn, 

Colusa, and Lake Counties, California: U.S. Geol. Survey Mineral Inv. 

Field Studies Map MF-279.

Brown, R. D., Jr., and Rich, E. I., 1961, Geologic map of the Lodogo quadrangle, Glenn and Colusa Counties, California: U.S. Geol. Survey Oil 

and Gas Inv. Map OM-210.

Brown, Eugene, Skougstad, M. W., and Fishman, M. J., 1970, Methods for 

collection and analysis of water samples for dissolved minerals and 

gases: U.S. Geol. Survey Techniques of Water-Resources Investigations, 

book 5, chap. A-l, 160 p.

Everhart, D. L., 1946, Quicksilver deposits at the Sulphur Bank mine, Lake 

County, California: California Jour. Mines and Geology, v. 42, p. 125-153.

_____1950, Skaggs Springs quicksilver mine, Sonoma County, California: 

California Jour. Mines and Geology, v, 46, no. 3, p. 385-394.

Hinkle, M. E., 1971, Determination of mercury in crude oils, in Geological 

Survey Research 1971: U.S. Geol. Survey Prof. Paper 750-B, p. B171- 

B174.

Hinkle, M. E., and Learned, R. E., 1969, Determination of mercury in natural 

waters by collection on silver screens, in Geological Survey Research 

1969: U.S. Geol. Survey Prof. Paper 650-D, p. D251-D254.

Irwin, W. P., 1960, Geologic reconnaissance of the northern coast Ranges and 

Klamath Mountains, California, with a summary of the mineral resources: California Div. Mines and Geology Bull. 179, 80 p.

Luce, R. W., 1971, Brucite identified as crystallizing from a natural cold 

alkaline spring gel: Clays and Clay Minerals, v. 19, no. 5, p. 335-336.

McNitt, J. R., 1968, Geology of the Lake Port quadrangle, Lake County, California: California Div. Mines and Geology map sheet 10.

Moiseyev, A. N., 1968, The Wilbur Springs quicksilver district (California) 

example of a study of hydrothermal processes by combining field geology 

and theoretical geochemistry: Econ. Geology, v. 63, p. 169-181.

Rich, E. L, 1971, Geologic map of the Wilbur Springs quadrangle, Colusa 

and Lake Counties, California: U.S. Geol. Survey Misc. Geol. Inv. Map 

1-538.

Rudkin, G. H., 1968, Natural gas in San Joaquin Valley, California, in Natural gases of North America Pt. 1, Natural gases in rocks of Cenozoic 

age: Am. Assoc. Petrol. Geologists Mem. 9, v. 1, p. 113-134.

Swe, Win, and Dickinson, W. R., 1970, Sedimentation and thrusting of late 

Mesozoic rocks in the Coast Ranges near Clear Lake, California: Geol. 

Soc. America Bull., v. 81, p. 165-188.

Vaughn, W. W., and McCarthy, J. H., Jr., 1964, An instrumental technique 

for the determination of submicrogram concentrations of mercury in 

soils, rocks, and gas, in Geological Survey Research 1964: U.S. Geol. 

Survey Prof. Paper 501-D, p. D123-D127 [1965].
NATURAL FLUIDS, MERCURY DEPOSITS, CALIFORNIA A19

Ward, R. N., and McHugh, J. B., 1964, Determination of mercury in vegetation with dithizone a single extraction procedure, in Geological Survey 

Research 1964: U.S. Geol. Survey Prof. Paper 501-D, p. D128-D130 

[1965].

Waring, G. A., 1915, Springs of California: U.S. Geol. Survey Water-Supply 

Paper 338, 410 p.

White, D. E., 1957, Magmatic, connate, and metamorphic waters: Geol. Soc. 

America Bull., v. 68, p. 1659-1682.

 1965, Saline waters of sedimentary rocks, in Fluids in subsurface 

environments A symposium: Am. Assoc. Petrol. Geologists Mem. 4, 

p. 342-366.

.1967, Mercury and base-metal deposits with associated thermal and

mineral waters, in H. L. Barnes [ed.], Geochemistry of hydrothermal

deposits: New York, Holt, Rinehart, and Winston, 575-631. 

White, D. E., Hem, J. D., and Waring, G. A., 1963, Chemical composition of

subsurface waters: U.S. Geol. Survey Prof. Paper 440-F, 67 p. 

White, D. E., Muffler, L. J. P., and Truesdell, A. F., 1971, Vapor-dominated

hydrothermal systems compared with hot-water systems: Econ. Geology,

v. 66, p. 75-97. 

White, D. E., and Roberson, C. E., 1962, Sulphur Bank, California, a major

hot-spring quicksilver deposit, in A. E. J. Engels and others [eds.],

Petrologic studies A volume to honor A. F. Buddington: Geol. Soc.

America, p. 397-428. 

Yates, R. G., and Hilpert, L. S., 1946, Quicksilver deposits of Eastern

Mayacmas district, Lake and Napa Counties, California: California

Jour. Mines and Geology, v. 42, no. 3, p. 231-286.

* U.S. GOVERNMENT PRINTING OFFICE: 1973 SIS 658/21