Mariposa Quadrangle, Mariposa anCJ 

Madera Counties, California----<: 

Analytic Data 

Mariposa Quadrangle, Mariposa and 

Madera Counties, CaliforniaAnalytic Data 

By KONRAD B. KRAUSKOPF 

Modal and chemical data on 

plutonic rocks of the 

Mariposa quadrangle 

U.S. GEOLOGICAL SURVEY BULLETIN 1613 
DEPARTMENT OF THE INTERIOR 

WilliAM P. ClARK, Secretary 

U.S. GEOlOGICAl SURVEY 

Dallas l. Peck, Director 

UNITED STATES GOVERNMENT PRINTING OFFICE 1984 

For safe by the 

Distribution Branch, Text Products Section 

U.S. Geological Survey 

604 South Pickett St. 

Alexandria, VA 22304 

library of Congress Cataloging in Publication Data 

Krauskopf, Konrad Bates, 1910-

Mariposa quadrangle, Marrposa and Madera Counties, 

California-analytic data 

(U.S. Geological Survey Bulletin 1613) 

Bibliography: p. 2. 

Supt. of Docs. no.: I 19.3:1613) 

1. Rocks, igneous. 2. Petrology-California-Mariposa 

County. 3.Petrology-California-Madera County. I. 

Title. II. Series: United States. Geological Survey. 

Bulletin 1613. 

QE75.B9 no. 1613 557.3s 84-600059 

[QE461] [552' .3'0979446] 
Abstract 1 

Introduction 1 

General geology 1 

Sampling and analytical methods 1 

Tonalite of Blue Canyon 2 

Other granitic rocks 2 

Ages 2 

References cited 2 

FIGURES 

1-6. Simplified geologic maps of the Mariposa quadrangle, 

showing: 

1. Locations of analyzed data 6 

2. Volume percentages of quartz 8 

3. Volume percentages of feldspar 9 

4. Volume percentages of mafic minerals 10 

5. Values of 100hornblende/(biotite+hornblende) 11 

6. Bulk densities 12 

7. Plots of modes of granitic rocks 13 

TABLES 

1. Chemical analyses, modes, and norms of samples from the 

Mariposa quadrangle, California 14 

III 

Mariposa Quadrangle, Mariposa and 

Madera Counties, California-Analytic Data 

By Konrad B. Krauskopf 

Abstract 

About ZZO samples of the plutonic rocks of the 

Mariposa quadrangle were collected during geologic 

mapping. All the samples were analyzed modally, and 

11 were analyzed chemically. The tonalite of Blue 

Canyon, which forms the principal plutonic body in the 

quadrangle, ranges in composition from granite to diorite, and transitions between varieties are gradational. The distribution of different varieties shows no 

regular zoning but apparently is somewhat influenced 

by the composition of adjacent metamorphic rocks. 

The presence of subhedral to euhedral hornblende and 

biotite crystal!:. in large parts of the tonalite of Blue 

Canyon is interpreted to indicate abundant water in 

the melt phase of the magma during crystallization, 

and the paucity of magnetite suggests a low oxygen 

fugacity. 

Radiometric ages of the plutonic rocks, based 

chiefly on values for samples collected from the same 

plutons in adjacent quadrangles, are approximately 114 

m.y. for the tonalite of Blue Canyon and the leucotonalite of Ward Mountain, about 111 m.y. for the leucotonalite north of Eastman Lake, and about 105 m.y. for 

the tonalite of Oakhurst. 

INTRODUCTION 

The Mariposa quadrangle is in the western foothills of the Sierra Nevada, about 50 km southwest of 

Yosemite Valley. State Highway 140, the main access 

road to Yosemite from the west, crosses the northwest 

corner of the quadrangle. State Highway 49, the 

Mother Lode highway, runs east-west across the northern part of the quadrangle. Both of these highways 

and a network of county roads provide access to all 

parts of the quadrangle. The town of Mariposa in the 

northwest corner and the nearby village of Bootjack 

are the only organized communities. 

This report supplements the geologic map of the 

quadrangle (Krauskopf, 1984) by providing modal and 

chemical data on the plutonic rocks. The data are presented below in maps, diagrams, and table (figs. 1-7; 

table 1), and the brief text is intended as a guide to 

understanding and interpreting the data. A nontechnical summary of the general geology of the quadrangle accompanies the geologic map. 

GENERAL GEOLOGY 

The entire Mariposa quadrangle is underlain by 

plutonic and metamorphic rocks. The metamorphic 

rocks occupy two principal areas-a wide strip along 

the west side and a large area in the east-central part 

of the quadrangle. The first area is part of the foothill 

metamorphic belt that extends north-south continuously for 300 km along the Sierra foothills, and the second 

area is part of the Coarsegold septum. 

The largest granitic body in the quadrangle is 

the tonalite of Blue Canyon, which occupies the 

central part of the quadrangle and extends into 

adjacent quadrangles on all four sides. The granitic 

rocks vary in texture and composition, and boundaries 

between the different varieties are gradational. A 

nearly identical rock unit, the tonalite of Oakhurst, 

forms a large pluton in the adjacent quadrangle (Bass 

Lake) to the east, and the edge of this pluton extends 

into the Mariposa quadrangle on the east margin. 

Two bodies of leucotonalite extend into the 

southwestern and southeastern parts of the quadrangle. The southwestern body is designated the 

''leucotonalite north of Eastman Lake" on the Raymond 

quadrangle map and is correlated with the granodiorite 

of Knowles (Bateman and others, 1981); the southeastern body is herein mapped as part of the leucotonalite 

of Ward Mountain. Diorite and gabbro crop out in 

small areas in many parts of the quadrangle. Serpentinized ultramafic rocks accompany the prong of metamorphic rocks near Mariposa and appear in small 

bodies elsewhere. 

SAMPLING AND ANALYTICAL METHODS 

Figure 1 shows the locations of 223 samples of 

typical plutonic rocks in the Mariposa quadrangle that 

were collected at an average spacing of 1.6 km, using 

care to obtain fresh and representative samples of the 

rocks at each locality. All the samples were analyzed 

modally, and 11 were analyzed chemically (samples 

MA8-MC49, table 1). Analyses of three other specimens from the tonalite of Blue Canyon are also listed 

in table 1 (samples C-CR5 to C-GR19). These specimens are from drill cores obtained in an earlier 

investigation (Saucier and Crisp, 1969); because they 

are located only by section number, they are not 

included on the maps or diagrams. Of the modal analSampling and Analytical Methods 1 
yses, 216 were made by combining the point counts of 

selectively stained slabs (Norman, 1974) with those of 

thin sections, and 7 modes were estimated from thin 

sections only. At least 1,000 regularly s~aced points 

were counted on slabs with areas of 70 em or more to 

determine the volume percentages of quartz, K-feldspar, plagioclase, and total mafic minerals. Relative 

amounts of biotite and hornblende were then determined on thin sections and apportioned to the total 

content of mafic minerals. Isopleths were drawn on 

figures 2 through 6 to bring out systematic patterns, 

but contouring was not attempted in areas where differences in the values are unsystematic or slight. 

TONAIJTE OF BLUE CANYON 

The tonalite of Blue Canyon is a mediumgrained rock, with dimensions of its principal minerals 

commonly in the range 1-3 mm. On a large scale, the 

texture and composition are remarkably uniform, but 

locally the composition ranges from quartz diorite and 

diorite on the one hand to granodiorite and granite on the other. The rock is nowhere conspicuously porphyritic, but locally both hornblende and K-feldspar form 

crystals as much as 20 mm long. Mafic minerals generally make up more than 15 percent of the rock. 

Hornblende and biotite are both commonly present, 

with biotite in excess, but hornblende predominates 

locally and is completely absent in some varieties. 

The proportion of hornblende, calculated as lOOhornblende/(hornblende+biotite), increases with the 

total content of mafic minerals, from 0 at less than 10 

percent mafic minerals to 50 percent at about 40 

percent mafic minerals (fig. 7). Plagioclase, generally 

the dominant mineral, has compositions mostly in the 

range 35-50 percent anorthite. Normal zoning is 

common over a range of about 5 percent anorthite, but 

many specimens have a wider range, and some show 

conspicuous oscillatory zoning. Quartz in some 

specimens forms large crystals but more commonly 

appears as aggregates of small anhedral grains. Kfeldspar locally forms numerous small subhedral 

phenocrysts, especially in the northern part of the 

quadrangle, but generally is limited to small stringers 

between other crystals, and in many specimens is absent altogether. 

Compositional patterns are not clearly defined, 

but as a broad generalization the more felsic rocks 

(lower density, higher quartz, lower total mafic 

minerals, and higher biotite/hornblende ratios) appear 

in the south-central part and northeast corner of the 

quadrangle. More mafic varieties form one ill-defined 

belt from northwest to southeast and another from the 

southwest corner into the central part of the quadrangle. This distribution shows enough relation to the 

composition of adjacent metamorphic rocks and to 

areas of gabbro and diorite to suggest that the composition of the tonalite was to some extent influenced by 

the rocks which it intruded. 

As noted by Bateman and Sawka (1981) for this 

tonalite in the adjacent Raymond quadrangle to the 

south, the scarcity of magnetite as an accessory mineral despite a general abundance of mafic constituents 

suggests low f

0 in the magma, and the common pres- 2 

ence of subhedral to euhedral biotite and hornblende 

crystals indicates a relatively high content of water. 

OTHER GRANITIC ROCKS 

Rocks in the small segment of the Oakhurst 

pluton at the east border of the Mariposa quadrangle 

could be described in the same terms as the tonalite of 

Blue Canyon, except that in such a small area the variety of rocks displayed is more limited. 

The leucotonalite in the southwest corner of the 

quadrangle is a fine-grained light-colored rock con- taining biotite and muscovite in small amounts, but no 

hornblende. Locally, K-feldspar forms small (max 6 

mm), inconspicuous phenocrysts poikilitieally enclosing 

other minerals. 

The leucotonalite of Ward Mountain in the 

southeast corner of the quadrangle is also a lightcolored rock containing biotite and muscovite, but is 

coarser grained and shows conspicuous cataelastic 

structure. In much of the rock, biotite is concentrated 

in curious crescent-shaped aggregates of tiny anhedral 

flakes; the crescents are as much as several 

centimeters long. 

AGES 

Radiometric ages have been determined for one sample from the Mariposa quadrangle, the tonalite of 

Blue Canyon, collected from the west side of Ben Hur 

Road, 1.5 km south of Mormon Bar (UTM Zone n coordinates 41 48900 N., 239700 E.). Ages determined by 

the U-Pb method on zircon from this sample for the 

three ratios 206Pb/238u, 207 Pb/235u, 208Pb/232Th 

are, respectively, 118.5, 113.5, and 106.2 m.y. (field 

No. MA-l; Stern and others, 1981, p. 4). The K-Ar 

mineral age for this same sample was determined as 

114 m.y. on biotite and 118 m.y. on hornblende (R. W. 

Kistler, written commun., 1976). Combining the U-Pb 

values for this specimen with those for samples from 

adjacent quadrangles gives an approximate age of 114 

m.y. for the tonalite of Blue Canyon. From adjacent 

quadrangles, samples of the leucotonalite of Ward 

Mountain give an approximate U-Pb age of 114 m.y., 

and samples of the tonalite of Oakhurst give an age of 

105 m.y. (Stern and others, 1981). The leucotonalite 

north of Eastman Lake, if it can be correlated with the 

granodiorite of Knowles in the Raymond quadrangle to 

the south, has a U-Pb age of 111.5 m.y. (Bateman and 

Sawka, 1981). 

REFERENCES CITED 

Bateman, P. C., Busacca, A. J., Marchand, D. E., and 

Sawka, W. N., 1981, Geologic map of the Raymond 

quadrangle, Madera and Mariposa Counties, 

California: U.S. Geological Survey Geologic 

Quadrangle Map GQ-1555, scale 1:62,500. 

Bateman, P. C. and Sawka, W. N., 1981, Raymond 

quadrangle, Madera and Mariposa Counties, CaliMariposa Quadrangle, C&lifornia--AAalytie Data 
fornia-analytic data: U.S. Geological Survey 

Professional Paper 1214, 16 p. 

Krauskopf, K. B., 1984, Geologic map of the Mariposa 

quadrangle, Mariposa and Madera Counties, California: U.S. Geological Survey Geologic Quadrangle Map GQ-1586, scale 1:62,500. 

Norman, M. B., 1974, Improved techniques for selective staining of feldspar and other minerals using 

amaranth: U.S. Geological Survey Journal of Research, v. 2, no. 1, p. 73-79. 

Saucier, K. L. and Crisp, R. W., 1969, Tests of rock 

cores: Castle study area. California: U.S. Army 

Corps of Engineers Miscellaneous Paper C-69-16, 

128 P• 

Stern, T. W., Bateman, P. C., Morgan, B. A., Newell, 

M. F., and Peck, D. L., 1981, Isotopic U-Pb ages of 

zircon from the granitoids of the central Sierra 

Nevada, California: U.S. Geological Survey 

Professional Paper 1185, 17 p. 

Streckeisen, A. L., chairman, 1973, Plutonic rocks: 

Classification and nomenclature recommended by 

the lUGS Subcommission on the Systematics of 

Igneous Rocks: Geotimes, v. 18, no. 10, p. 26-30. 

References Cited 3 

FIGURES 1-7; TABLE 1 
830 • 

.G • GR 

.G .G 

.GR .G 

.G G" .D 

.D 

4 KILOMETERS 

3 MILES 

Figure 1. Mariposa quadrangle, showing principal bedrock units, locations of modally analyzed and chemically 

analyzed samples, and locations of samples of major granitoid types. 

6 Mariposa Quadrangle, california--Analytic Data 
EXPLANATION 

Leucotonalite north of Eastman Lake (Cretaceous) 

Leucotonalite of Ward Mountain (Cretaceous) 

Tonalite of Oakhurst (Cretaceous) 

Tonalite of Blue Canyon (Cretaceous) 

Diorite and gabbro (Cretaceous or Jurassic) 

Metasedimentary rocks (Mesozoic and 

Paleozoic)-Chiefly metasedimentary rocks, 

minor metavolcanic rocks 

• 

Metasedimentary rocks with abundant metalimestone (Mesozok: and Paleozoic) 

:~:~ :~ :~: :~:: :::::: :1 M::;~~~~~ ~d ultramafic rocks (Mesozoic 

---- Contact 

X 

MA-1 

ModaUy analyzed sample 

Chemk:aUy analyzed sample-D, quartz diorite; 

G, granodiorite; GR, granite; aU others, 

tonalite 

Sample dated by U- Pb method 

- 30- Isopleth-Showing volume percent. See tlgs. 2-6 

Figures 1-7; Table 1 7 
4 KILOMETERS 

3 MILES 

Figure 2. Mariposa quadrangle, showing volume percentages of quartz. Isopleth interval, 5 volume percent. 

See figure 1 for explanation. 

8 Mariposa Quadrangle, california--Analytic Data 
37'15' 

.50 .54 

• 54 

o52(4) 

52(2). 

"52(4) 

o51 (3) 

o49(1) 

Figure 3. Mariposa quadrangle, showing volume percentages of feldspar. Numbers without parentheses are 

volume percentages of plagioclase (An5_100), rounded to the nearest whole number. Numbers within 

parentheses are volume percentages of alkali feldspar, omitted where less than 0.5 volume percent. Thus, 

"54(3)" indicates a sample containing 54 volume percent plagioclase and 3 volume percent alkali feldspar; and 

"43" indicates a sample containing 43 volume percent plagioclase and less than 0.5 volume percent alkali 

feldspar. Isopleths show volume percentage of plagioclase; interval, 5 volume percent. See figure 1 for 

explanation. 

Figures 1-7; Table 1 9 
0 .21 

() .21 

.15 

.19 

.15 .16 .19 

.24 37'15' 

4 KILOMETERS 

3 MILES 

Figure 4. Mariposa quadrangle, showing volume percentages of mafic minerals. Isopleth interval, 5 volume 

percent. See figure 1 for explanation. 

10 Mariposa Quadrangle, C&lifornia--Analytic Data 
.25 n· .24 

• 25 

24 • .20 

~ "2 

"5 

.7 

.3 

"15 

'2-0 

25 .30 Q • 36 

4. KILOMETERS 

3 MILES 

Figure 5. Mariposa quadrangle, showing values of lOOhornblende/(biotite+hornblende). Isopleth interval, 20· .. 

See figure 1 for explanation. 

F:igares 1-7; Table l 11 
~ .72 

.72 

.72 .73 .73 .72 

.74 .74 

.74 

.72 .71 

37'15' .73 .74 74 .72 • 73 

4 KILOMETERS 

3 MILES 

Figure 6. Mariposa quadrangle, showing bulk densities (in grams:fer cubic centimeter). Numbe~s are decimals 

that follow "2"; thus, "75" indicates a bulk density of 2.75 g/cm • Isopleth interval, 0.05 g/cm • See figure 1 

for explanation. 

12 Mariposa Quadrangle, california--Analytic Data 
• 

EXPLANATION 

• Tollllte of Blue Clnyon 

+ T ollllite of Olklllrst 

A LIUCOtellllitl of Wlfd Mountain 

o Laucotonllite north of Eatm111 Like 

Totel·modes: 

Tollllite 

Granodiorite 

Granite 

llulrtz diorite 

Total 

177 

24 

2 

20 

223 

• • • 

• ~· 

. ···' . .. • 

20 ',_._,,.. 

i • . 

~·· ..... 

• • • .. . .... • J "·; :·. 

• • • • • • • 

•A ... ~. • ••• .. :, .. • 

• • • 

• . • • 

• . ... • • .. : . .. '• • ·" ,. . , ., •• • • • 

•40 • • • .. • 

• • 

• 

• • • 

• 50 

llulrtz 

Granite 

lluert monzonite 

Figure 7. Modes of granitic rocks. Classification scheme by Streckeisen (1973). 

Figures 1-7; Table 1 13 
Table 1. Chemical analyses, modes, and norms of samples from the Mariposa quadrangle. 

[Chemical analyses for samples MAS to MC49 and MC15 to MA48 by X-ray spectroscopy; 

analysts: J. S. Wahlberg, J. Taggart, J. Baker, and D. Shepard; supervisors: J. S. Wahlberg and J. 

M. Baldwin. Modal analyses of felsic minerals and total mafic minerals ~termined by counting 

1,000 to 2,000 points on selectively stained slabs of at least 70-cm area; analyst, Oleg 

Polovtsoff. Hornblende and biotite determined by apportioning counts on thin sections to total 

mafic minerals. Chemical analyses for samples C-CR5 to c-cR19 by rapid rock method; 

analysts: J. Elmore, H. Smith, G. Chloe, J. Glenn, J. Kelsey; supervisor: L. Shapiro. Modal 

analyses by counting on thin sections; analyst, P. C. Bateman] 

S.tmplj• no4-- MA8 MAll MA44 HB30 MC19 MC21 MD) MC49 C-CR) C-CRIO C-CR19 __,MC:::.;1'-'!5 __ MA=2::..6 _ _,MA=4 7,_____,MA=48::.___ 

l<uck nam•·--- _______ T'-"o'-"'na"-'l-"it'-"e ____ __,o'-'.f ___ _.:B~lu::.:oe ______ ....::C:::.an:=;on::_ _____________ O::..:t::..:;he:o:<..::.•------

Rock typt.•--- Tona- Tnna- T1)na- Grano- Tona- Tona- Tona- Tona- Quartz Tona- Quartz. 

lite lite lite -diorite lite lite lite lite diorite lite diorite 

Locat inn----

s i02 --------

A ':~0 3 -------

F ~:!0] -------

FeO---------

MgO---------

Na2o-------.. 

K2o:--------

u2o _ --------

ll2o --------

Tio2 --------

P 2o,--------

Mno---------

cor--------

59.4 

17 .& 

l.!'i 

4.65 

).47 

6.84 

3.17 

1.43 

.92 

.14 

• 79 

.18 

.! 

.18 

Total---- 100. I 

Quartz------ IS 

K-feldspar--

Plagioc Lase- 53 

Mafic minerals 

Biotite--- 20 

Ho-rnblende 12 

Hypersthene --

Total--- 100 

Bulk density 2.80 

(g/cm3 J 

64.4 

16.4 

.82 

3.49 

2.30 

4.67 

3.24 

2.45 

.96 

.17 

.ss 

.14 

.07 

.19 

61.3 

16.6 

I. 3R 

4. 38 

3.24 

). 91 

3.ll 

1.84 

.9) 

.ll 

.77 

.18 

.I 

.32 

67.7 

15.2 

.8) 

2.6) 

1.80 

3.S3 

2.86 

3. 77 

.63 

.11 

.50 

.l 

.05 

.07 

See figure 1 

T.5 S. 

R.l9 E. 

sec. 28 

Chemical analyses (weight percent) 

66.2 

16.2 

1.26 

2.5) 

1.8) 

4.46 

3.44 

2.05 

.88 

.21 

.48 

.15 

.07 

.16 

61.8 

17.1 

1.06 

4.3) 

3.13 

6.07 

3.41 

1.46 

1.00 

.12 

.68 

.13 

.09 

.09 

61.9 

!).9 

.86 

4.43 

3.94 

5.17 

3.36 

2.37 

1.13 

.16 

.77 

.19 

.08 

.12 

60.4 

17.7 

.82 

4.48 

3.36 

6.)) 

3.36 

1.32 

!.15 

.12 

.69 

.17 

.09 

.16 

67.1 

17.0 

.66 

2.67 

1.66 

4.46 

3.99 

1.31 

.80 

.10 

.S1 

.IS 

.05 

.19 

60.1 

17.1 

• 70 

).0 

3.3 

6.1 

3.2 

1.7 

1.1 

.14 

.88 

.18 

.13 

<.05 

T.6 S. 

R.l9 E. 

sec~ 34 

)4.2 

18.7 

.00 

7.2 

4.3 

6.9 

3.4 

2.4 

1.2 

.ll 

.93 

.26 

.IS 

<.OS 

99.9 100.2 99.8 100.0 100.) 100.4 100.4 100.6) 100.0 100.0 

23 

so 

13 

lO 

100 

l3 

45 

24 

17 

100 

27 

16 

3) 

15 

100 

2. 73 2. 78 2. 70 

29 

49 

100 

2. 72 

15 

)) 

17 

13 

100 

2. 76 

Modes (volume percent) 

16 

47 

23 

13 

100 

2-77 

18 

49 

14 

19 

100 

2. 77 

12 

18 

100 

2.14 

CIPW Norms (weight percent) 

2) 

S1 

24 

100 

IS 

60 

25 

100 

Tona- Grano- Hyper- Meta- Serpenlite dio.ri te sthene dacite tine 

T. 7 S. 

R.20 E. 

sec. 28 

66.4 

16.4 

.14 

3.6 

1.8 

4.) 

3.5 

1.9 

.77 

.13 

.50 

.11 

.07 

<.OS 

100.0 

34 

so 

IS 

100 

South of 

Green 

Mountain 

73.4 

1).2 

.HI 

.94 

.48 

2.26 

3.98 

2.40 

.33 

.04 

.1) 

-07 

<.02 

.o8 

99. s 

4() 

46 

100 

2.67 

diorite 

Valley West 

of edge of 

Humbug quadCt'eek ran le 

)6.6 

18.9 

1.64 

).28 

4.30 

7 .~6 

3.37 

.49 

.46 

.14 

.88 

.19 

-12 

.14 

79.4 

10.2 

.28 

.96 

1.S2 

2.01 

2.28 

1.84 

.f>7 

-06 

.44 

.o9 

.o2 

.28 

3 km East 

of Mari44.1 

1.45 

3.66 

4.6) 

39.42 

.I 

<.15 

<.02 

5.29 

.51 

<.02 

<.0) 

.13 

.22 

100.) 100.1 <99.8 

tt 

70 

lOO 

2.85 

Q----------- 14.08 21.19 17.22 25.35 25.42 16.87 14.82 14.84 2).74 14.76 .16 24.37 3).)9 9.36 52.89 .oo 

c----------- .oo .27 .oo .24 .S8 .oo .oo .oo 1.21 .oo .oo .67 2.13 .oo 1.03 1.36 

8.)6 14.70 11.01 22.Sl 12.28 8.69 14.1) 7.89 7.78 10.21 14.41 ll.35 14.32 2.90 10.98 .00 

ab---------- 27.1) 27.82 26.63 24.44 29.49 29.06 28.73 28.74 33.91 27.)2 29.23 29.94 34.00 28.)4 19.48 .00 

29.94 22.)9 26.21 17.03 21.42 27.24 21.52 29.63 21.24 27.72 29.ll 21.84 10.86 35.02 9.48 .53 

di---------- 2.6> .00 1.86 .00 .00 1.84 2.56 1.72 .00 1.52 3.26 .oo .oo 2.6) .oo .oo 

hy---------- 14.00 10.84 13.14 7.99 7.69 13.15 1).03 14.26 7.78 1).12 21.41 10.40 2.62 17.04 4.b7 47.84 

mt---------- 1.69 1.21 2.03 1.25 1.8) !.S5 1.26 1.20 .96 1.03 .00 .21 .26 2.38 .41 5.68 

il·--------- 1.)2 1.06 1.48 .96 .92 1.30 1.48 1.33 .97 1.70 1.79 .96 .2) 1.67 .84 .oo 

ap---------- .43 .34 .43 .24 .36 .31 .46 1.41 .36 .43 .63 .26 .11 .45 -22 .00 

ol---------- .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 44.60 

Total--- 100.02 100.02 100.01 100.01 100.01 100.01 100.01 101.02 100.01 100.01 100.02 100.00 100.00 100.01 100.00 100.01 

Estimate from thin sect ion, not point count-ed. 

t Sample MA47 consists of quartz, plagioclase, actinolite, and biotite. Sample was not point counted. 

tt San~ple MA48 consists of olivine, anthophyllite, and antigorit-e~ Sample was not point counted~ 

14 Mariposa Quadrangle, CBiifornia--Analytic Data 

GPO 787~042/10004