SMITHSONIAN CONTRIBUTIONS TO THE

EARTH SCIENCES

NUMBER 3

Brian Mason Minor and Trace

and A. L. Graham p i t

Elements m

Meteoritic

Minerals

SMITHSONIAN INSTITUTION PRESS

CITY OF WASHINGTON

1970
ABSTRACT

Mason, Brian and A. L. Graham. Minor and Trace Elements in Meteoritic Minerals.

Smithsonian Contributions to the Earth Sciences, 3:1—17. 1970.—Nickel-iron,

troilite, olivine, pyroxenes, plagioclase, chromite, and phosphate minerals (chlorapatite and/or merrillite) have been separated from a number of meteorites (Modoc,

St. Severin, Winona, Haraiya, Marjalahti, Springwater, Johnstown, Mt. Egerton,

Soroti) and analyzed for minor and trace elements with the spark-source mass

spectrometer. The elements Ni, Go, Ge, As, Ru, Rh, Pd, Sn, Sb, W, Re, Os, Ir, Pt,

and Au are concentrated in nickel-iron: Se and Ag in troilite; Th, U, and the

lanthanides in the phosphate minerals and in diopside; Eu, Sr, Ba, Rb, and Gs in

plagioclase. Molybdenum and tellurium are concentrated in nickel-iron and troilite.

The elements Ti, Sc, V, Cu, Zn, Mn, and Ga are distributed over several coexisting

minerals.

Official publication date is handstamped in a limited number of initial copies and is recorded

in the Institution's annual report, Smithsonian Year.

UNITED STATES GOVERNMENT PRINTING OFFICE

WASHINGTON : 1970

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

Washington, D.C. 20402 - Price 30 cents (paper cover)
Brian Mason

and A. L. Graham

Minor and Trace

Elements in

Meteoritic

Minerals

Introduction

During the past decade a very large amount of data

has been accumulated on the abundances of minor and

trace elements in meteorites, and adequate information is now available on abundance levels of practically

all elements for the different classes of meteorite. The

distribution of these elements, however, among the individual phases (minerals) of the meteorites is less well

known. This can be ascribed in part to the unavailability of large enough samples of many meteorites

(especially of the rarer classes) for mineral separation,

and in part to the difficulty of making clean separations

of the fine-grained minerals in many meteorites, particularly the chondrites. The chondrites are, of course,

of special interest, since they represent the least fractionated group of meteorites, and contain many minor

and trace elements in amounts comparable to solar

abundances.

Some significant information has been obtained by

the analysis of magnetic (e.g., metallic) and nonmagnetic (e.g., sulfide plus silicate) fractions of chondritic meteorites (see, for example, Onishi and

Sandell (1956), Wardani (1957), Shima (1964),

Fouche and Smales (1967). This procedure, however,

is useful only for distinguishing the extremely siderophile elements, and provides no information on the distribution of the other elements within the individual

minerals. Refined techniques of selective solution of

the different phases have been applied to chondrites by

Brian Mason, Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560. A. L. Graham, Department of Geophysics

and Geochemistry, The Australian National University, Canberra, Australian Capital Territory, 2600.

Vilcsek and Wanke (1965) and Honda and Shima

(1967) ; however, study of their results indicates that

this selective solution is seldom completely quantitative.

Moss et al. (1967) have developed a selective decomposition procedure, based on heating a meteorite

sample in a stream of dry chlorine, which enables

measurement of a number of elements in metal, sulfide,

and silicate phases.

The introduction of the electron-beam microprobe

has made it possible to measure the concentration of

many elements in the individual minerals in a polished

section of a meteorite, without the necessity of separating the individual minerals by physical or chemical

techniques. However, the lower detection limit of the

microprobe is about 100 ppm, whereas comparatively

few elements are present in the common minerals of

meteorites above that level.

The spark source mass spectrometer appears to be

an excellent tool with which to attack this problem. It

is extremely versatile, being capable of detecting all

elements from boron to uranium at concentrations of

the order of 0.1 ppm, and considerably less for some

elements. Sample requirements are comparatively

small: 100 mg is a convenient amount, but good results

can be obtained on samples of 10-20 mg. This is very

advantageous for chondritic meteorites, in which many

elements are concentrated in phases such as phosphates

(apatite and/or merrillite) and chromite, present in

amounts of less than 1 percent of the bulk meteorite.

Experimental

MINERAL SEPARATION.—As originally planned, the

principal objective of this research was to obtain comprehensive data on the distribution of minor and trace

1
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

elements among the minerals of the common chondrites. Preliminary experiments showed that to obtain

adequate samples of accessory minerals such as chromite and the phosphates it would be necessary to start

with about 100 g of the meteorite. This limited the selection to chondrites available in considerable amounts.

Since terrestrial weathering would be a complicating

factor, only fresh falls were considered. Ultimately two

were selected from the meteorite collection of the

Smithsonian Institution, Modoc (NMNH 360), a

hypersthene chondrite belonging to the L6 group of

Van Schmus and Wood (1967), and St. Severin

(NMNH 2608), a hypersthene chondrite (amphoterite subclass) belonging to the LL6 group. General descriptions of these meteorites, with bulk analyses, have

been published: Modoc (Mason and Wiik, 1967) ; St.

Severin (Jarosewich and Mason, 1969).

A crust-free piece weighing about 100 g was cut from

each of these meteorites. The pieces were broken into

smaller fragments which were carefully crushed in a

hardened steel mortar until all the material passed

through a 10-mesh sieve. Further crushing in a large

agate mortar reduced all the material to —100 mesh,

except for coarse metal particles, which were removed

with a hand magnet. We found the optimum size for

mineral separation was the —200 +325 mesh fraction,

except for the metal, most of which was coarser than

200 mesh, and for which the —100 +200 fraction was

used.

The —200 +325 fraction was sedimented in a

large beaker with distilled water to remove dust. Metallic particles were removed with a magnet from the

dried fraction, after which this fraction was separated

into two portions by centrifuging in pure CH2I2

(D = 3.32). The denser portion consisted largely of

olivine and pyroxene, with minor amounts of troilite

and chromite; the less dense portion contained the

plagioclase and phosphate minerals; both portions still

contained a considerable quantity of composite grains.

Pure plagioclase was obtained by extracting a fraction with D<2.70 (centrifugation in CH2I2-acetone

mixture), purification of this fraction with the Frantz

Isodynamic Separator, and boiling the final separate

in HC1 to remove any adhering acid-soluble minerals.

The phosphate minerals were concentrated in the

fraction with D = 3.08-3.20, followed by passage

through the isodynamic separator at full power, the

phosphate being entirely nonmagnetic. Only small

samples of about 20 mg each were recovered.

The portion with D>3.32 was further fractionated

using Clerici solution of controlled density. Hypersthene concentrated in the 3.32-3.45 fraction, olivine

in the 3.50-3.60 fraction; chromite and troilite formed

the fraction with D>4.0. These fractions were further processed with the isodynamic separator, yielding

reasonably pure separates of hypersthene, olivine,

troilite, and chromite. The hypersthene and chromite

fractions were further treated with hot HC1 to remove

any adhering olivine and troilite.

The 100-200 mesh magnetic fraction, consisting of

metal particles with adhering silicates, was placed in

a beaker of acetone and agitated repeatedly in an

ultrasonic cleaner. The silicates were separated from

the metal by magnetic separation (Modoc), and by

centrifugation in Clerici solution (St. Severin).

The purity of these mineral separates was evaluated

by microscopic examination. The Modoc fractions were

uniformly purer than those from St. Severin, this being

conditioned by the somewhat coarser crystallinity of

Modoc. Notes on the individual minerals follow.

Modoc olivine: about 99 percent pure; impurity

mainly pyroxene; some grains contain minute opaque

inclusions, probably chromite; slight limonite staining

on many grains.

Modoc hypersthene: about 98 percent pure; impurities are tiny inclusions of plagioclase and admixed

grains of diopside.

Modoc feldspar: about 99 percent pure; principal

impurity is pyroxene, as tiny inclusions; a few grains

show a small amount of opaque dust, probably

chromite.

Modoc troilite: about 98 percent pure, impurities

are olivine and pyroxene.

Modoc chromite: about 99 percent pure; impurity

is mainly pyroxene.

Modoc metal: about 95 percent pure; principal

impurities are olivine and pyroxene.

Modoc phosphate: about 99 percent pure; impurities are tiny inclusions of olivine, pyroxene, and

plagioclase.

The impurities in the St. Severin separates were

essentially the same as the corresponding Modoc separates, but the estimated purity was lower, viz, olivine,

97 percent; hypersthene, 95 percent; feldspar, 96 percent; troilite, 94 percent; chromite, 98 percent; metal,

90 percent; phosphate, 98 percent.

In order to provide comparative material from other

classes of meteorites, the following mineral concen-
NUMBER 3

trates were prepared from the meteorites listed, using

techniques similar to those described above:

Olivine: Marjalahti (Fa12), Springwater (Fa18).

Orthopyroxene: Winona (Fs(!), Johnstown (Fs27),

Mt. Egerton (Fs0).

Diopside: Winona.

Pigeonite: Haraiya.

Plagioclase: Winona (AnTM), Haraiya (An90).

Troilite: Soroti.

Marjalahti and Springwater are pallasites, Johnstown a hypersthene achondrite, Mt. Egerton an enstatite achondrite, Haraiya a eucrite, Soroti a troiliterich iron. Winona is a peculiar meteorite, having

chondritic composition but lacking chondritic structure (Mason and Jarosewich, 1967).

To provide a comparison with terrestrial minerals,

olivine, orthopyroxene, and diopside were separated

from a peridotite xenolith in a basalt at Camperdown,

Victoria, Australia.

ANALYSIS WITH THE SPARK-SOURCE MASS SPECTROMETER. The mass spectrograph used was the M.S.7,

manufactured by Associated Electrical Industries Ltd.

(now GEC-Elliott Automation). It utilizes double

focusing geometry for the ion path and photographic

recording of the mass spectrum. The ion source is a

pulsed R.F. spark passed between two electrodes, which

have been pressed from a 50:50 mixture of sample

powder and a graphite/Lu2O3 mix. The ion path is

maintained at a vacuum of the order of 10~8 torr, as

higher pressures cause excessive background on the

photoplates.

Each mineral separate was ground in an agate

mortar until further grinding had no appreciable

effect upon the degree of subdivision of the material.

Sample homogeneity is one of the major problems

when using this analytical technique. The sensitivity

of the method is such that a weight of sample of about

0.1 mg is burnt during each analysis and it must be

truly homogeneous. Nicholls et al. (1967) fused the

sample with a flux to achieve a satisfactory degree of

homogeneity. In this study we were dealing with silicate, sulfide, and metal phases and fusion of the

meteorite fractions was not feasible owing to the

immiscibility of the sulfide and the metal phases with

silicate fluxes.

Following Taylor (1965), the finely ground samples

were mixed with an equal weight of graphite/Lu2O3

mix. The lutetium oxide was present in the graphite

at 50 ppm by weight Lu2O3 and was the internal

standard in the analysis. The geochemical standards

Gl and Wl were each equally mixed with the same

graphite/Lu2O3 mix and sparked under identical conditions. The mass spectrum for each sample was

recorded on an Ilford 02 photoplate which was

subsequently processed in accordance with the manufacturers' instructions. Fifteen exposures were taken

on each plate and exposure was measured in units of

charge, as, owing to the fluctuations of the intensity

of the ion beam, a fixed time may not give a consistent

exposure. The normal procedure when sparking a

sample for an exposure range of 1:1000 was for the

spark parameters, the repetition rate and length, to be

varied such that the recording devices were operated

under their optimum conditions. Unfortunately,

changing the sparking conditions produces a change

in the relative sensitivities of the elements. To avoid

this the conditions of the R.F. discharge of the spark

were kept constant, the ion beam being attenuated

when necessary by the use of an electrical "chopping"

device.

The intensity of the lines used for analysis was

read on a Jarrall-Ash microphotometer. These intensities were plotted against exposure, and the exposure

required to produce a line of a given, fixed intensity

was read from this curve. The lutetium 175 line was

used as the internal standard and the exposure required to produce the same given intensity was read

from a similarly plotted curve. From the standard

plates of Gl and Wl, graphs were drawn of ppm

against where Ex is the exposure required to

E175

produce a line of given intensity for the isotope X.

El75 is the exposure required to produce a line of the

same given intensity for

 175Lu.

For each sample Ex and El75 were found by reading the photoplate and plotting the intensities against

exposure. The concentration of the element of which

X is an isotope was then determined from the graphs

relating to ppm X produced from the Gl and Wl

Hi A / *j

standard plates. Table 1 gives the mass lines used for

the estimation of each element reported here.

The detection limit is fixed by the length of exposure

of the plate to the ion beam produced from the

sample, and also by the proportion of the element in

question that is present as the isotope whose line

intensity is measured in the analysis. If 20 percent of
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

TABLE

Element

B

F

Cl

Sc

Ti

V

Cr

Mn

Co

Ni

Cu

Zn

Ga

Ge

As

Br

Rb

Sr

Y

Zr

Nb

Mo

1.—Mass lines used for element

Mass lines

11

19

35

45

47

51

53

55

59

62

63,65

66,67

69,71

74

75

79

85

86,88

89

90,91

93

95,98

Element

Sn

Sb

Cs

Ba

La

Ce

Pr

Nd

Sm

En

Gd

Tb

Dy

Ho

Er

Tm

Yb

Hf

Pb

Th

U

estimation

Mass lines

117, 118

123

133

135, 137, 138

139

140

141

143, 146

147, 149

151, 153

155, 157, 158

159

161, 163

165

166, 167

169

172, 173, 174

177, 178, 179

208

232

238

TABLE 2.—Element abundances used as standards

[ppm by weight]

an element X is present as one isotope, and this

isotope is used in the determination of the concentration of X, for a given exposure the detection limit of

X is five times that of a second element Y which has

only one isotope. In this work, the detection limit was

set at approximately 0.1 ppm atomic for mono-isotopic

elements, i.e., the exposure range selected was between 0.1.10"9

 and 100.10"9 coulombs.

The accuracy of the figures are dependent upon the

values accepted for the geochemical standards used

for calibration, and upon the purity of the mineral

separates. The latter has been discussed already and

the values used for standardization are given in Table

2. One plate was run for each sample and the fifteen

graded exposures on each plate gave four or five points

on the intensity/exposure graph. The resulting precision is of the order of ± 20 percent.

Elemental Abundances in Separated Minerals

Boron: This element is present in measurable

amounts in the feldspar (f) and olivine (o) separates,

as follows (in ppm) : Modoc, 2(f) 3(o) ; St. Sever-in,

3(f) 2(o) ; Winona, 5(f); Haraiya, 2(f); Marjalahti,

Element

B

F

Cl

Sc

Ti

V

Cr

Mn

Co

Ni

Cu

Zn

Ga

Ge

As

Rb

Sr

Y

Zr

Nb

Gl

1.5

700

100

2.8

1,560

15

20

230

2.3

1.2

13

45

19

1. 1

0.7

220

260

13

210

21

Wl

12

200

200

34

6,400

250

115

1,300

45

75

115

83

16

1.7

2.4

22

180

26

95

10

Element

Mo

Cs

Ba

La

Ce

Pr

Nd

Sm

Eu

Gd

Tb

Dy

Ho

Er

Tm

Yb

Hf

Pb

Th

U

Gl

7.5

1.5

1,050

100

170

17

55

9.0

1.4

6.9

0.70

5.3

0.50

1.4

0.20

1.0

6.0

49

50

3.2

Wl

0.8

0.90

160

11.9

20

3.5

12.5

3.4

1. 1

3.0

0.60

4.0

0.80

2.08

0.28

2. 1

2.0

8

2.2

0.5

0.5 (o); Springwater, 3(o). Thus, in meteorites most

of this element evidently resides in the feldspar and

olivine, as might be predicted from the occurrence of

the the boron analogs of these minerals reedmergnerite

(NaBSI3O8) andsinhalite (MgAlBO4).

Fluorine: This element cannot be measured at the

low concentrations present in most meteoritic minerals,

due to interference from iron (1/3 Fe57). In the phosphate concentrates Modoc contained 880 ppm, St.

Severin 36 ppm; this remarkable contrast is evidently

due to the presence of apatite in the Modoc phosphate

and its practical absence in St. Severin.

Chlorine: Chlorine is a major constituent of the

Modoc phosphate, the amount being too great to measure with the mass spectrometer. Assuming the composition of chondritic apatite given by Van Schmus and

Ribbe (1969), then from the 880 ppm F the amount

of chlorine in the Modoc phosphate would be 1.2 percent, and this would contribute 60 ppm to the bulk

meteorite. St. Severin phosphate contains only 130

ppm, reflecting the practical absence of apatite.

Chlorine was measured in the metal phases (Modoc,

74 ppm, St. Severin, 52 ppm), suggesting the presence

of occluded lawrencite (Fe, Ni) Cl2. It was also found

in the troilite (Modoc, 13 ppm; St. Severin, 29 ppm;
NUMBER 3

Soroti, 39 ppm). It was not detected in olivine; in the

remaining separates the use of HC1 during separation

introduced possible contamination.

Scandium: This element was detected in all the

phases (Table 3), but the small amount in the metal

can probably be ascribed to silicate contamination.

Scandium is essentially lithophile, but shows some chalcophile affinity. In stony meteorites most of this element is contained in the pyroxenes, but the plagioclase

and olivine also carry a moderate proportion of the

total scandium. Although the abundances in the individual phases of the two chondrites are generally comparable, the variation between specific minerals in the

two chondrites is greater than expected, and the sum of

the amounts in the individual minerals from St. Severin

exceeds the amount measured in a bulk sample of this

meteorite. The figures for the Camperdown minerals

are similar to those for the meteoritic minerals.

Titanium: This element was detected in all the

phases (Table 4). However, the high concentration in

chromite and the possible presence of ilmenite means

that even slight contamination by these minerals in

the separates will greatly enhance the titanium figures.

Contamination is probably responsible for the high

and variable figures for plagioclase. Corlett and Ribbe

(1967) did not detect Ti at the 100 ppm level in

microprobe analyses of terrestrial plagioclases in the

Ano_3o and AnGO-ioo composition ranges. However, it

can be concluded from Table 4 that the major fraction

of titanium in meteorites is contained in pyroxenes;

meteoritic pyroxenes contain more titanium than

pyroxenes in the terrestrial peridotite from CamperTABLE 3.—Scandium {ppm)

Meteorite Metal Troilite Olivine Ortho- Clino- Plagioclase Chromite Phosphate

pyroxene pyroxene i

Bulk

Camperdown

Modoc

St. Severin. .

Winona

Haraiya

Marjalahti...

Springwater.

Johnstown...

Mt. Egerton.

Soroti

1

0.5 19

8

3

9

3

3

13

10

36

17

64

50

40

6

17

16

12

2

2

44

30

2 8. 1

9

23

10

J

In this and succeeding tables clinopyroxene is diopside in

Camperdown and Winona, pigeonite in Haraiya.

2

Schmittetal. (1964).

TABLE 4.—Titanium (ppm)

Meteorite Metal Troilite Olivine Ortho- Clino- Plagioclase Chromite Phosphate

pyroxene pyroxene

Bulk

Camperdown

Modoc

St. Severin. .

Winona

Haraiya

Marjalahti...

Springwater.

Johnstown...

Mt. Egerton.

Soroti

1 <50

1 <50

50

50

140

100

220

46

40

350

2 1, 000

2 1, 000

2 1, 200

1,200

120

1,

2 3,

2 2,

000

800

100

360

650

200

340

» 17,000

3 19, 000

2, 100

1,200

700

650

4 840

22

1

 Jarosewich (unpublished).

2

 Microprobe analysis.

3 Bunch et al. (1967).

* Mason and Jarosewich (1967).
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

down. The titanium figures for the Modoc and St.

Severin troilites are about half those determined byMoss et al. (1967) in troilite from three hypersthene

chondrites.

Vanadium: Bunch et al. (1967) showed that much

of the vanadium in chondrites is contained in the

chromite, and this has been confirmed in our study

(Table 5). Contamination by chromite may be responsible for the vanadium recorded in the metal and

troilite separates. Clearly the principal carriers of

vanadium, apart from chromite, are the pyroxenes,

clinopyroxene being richer in this element than orthopyroxene. The contents in the minerals of the terrestrial peridotite from Camperdown are comparable

with those for the meteoritic minerals. The low content

in the Mt. Egerton pyroxene reflects the chalcophile

character of vanadium under the extremely reducing

conditions of the enstatite achondrites.

Chromium: Possible contamination with chromite

is a serious problem, since 0.1 percent of this mineral

will add about 370 ppm Cr to any mineral separate.

Many of the data in Table 6 may be too high on this

account. The figures for troilite, however, are consistent with those published for iron meteorites and

troilite nodules. Smith (1966) reported microprobe

analyses for olivine from the Huckitta pallasite (330

ppm), and for olivine from Marjalahti (700 ppm) ; the

latter figure is much higher than our figure. The contrast between the pyroxenes from Modoc and St.

Severin may be of real significance and not due to inclusions; Modoc is notably rich in chromite, and therefore its pyroxene may be impoverished in this element.

TABLE 5.—Vanadium (ppm)

Meteorite Metal Troilite Olivine Ortho- Clino- Plagioclase Chromite Phosphate

pyroxene pyroxene

Bulk

Camperdown

Modoc

St. Severin...

Winona

Haraiya. . . .

Marjalahti...

Springwater.

Johnstown...

Mt. Egerton.

Soroti

4

5

9

9

14

10

23

55

40

120

33

120

1

310

100

74

12

30

5

9

i 4, 000

i 4, 000

5

12 54

Bunch et al. (1967).

TABLE 6.—Chromium (ppm)

Meteorite Metal Troilite Olivine Ortho- Clino- Plagioclase Chromite Phosphate

pyroxene pyroxene {percent)

Bulk

Camperdown

Modoc

St. Severin. .

Winona

Haraiya

Marjalahti...

Springwater.

Johnstown...

Mt. Egerton.

Soroti

2

< 1 0

2

 <10

140

270

370

350

330

180

270

i 2, 800

!800

^00

1

 1, 000

< 5, 600

80

i 9, 000

1

 4, 100

1

 4, 300

1

 4, 800

1

 1, 900

370

1,000

140

100

37

38

340

210

3 3, 800

* 3, 900

s 2, 000

730

1

 Microprobe analysis.

2

 Jarosewich (unpublished).

3 Mason and Wiik (1967).

4

 Jarosewich and Mason (1969).

5

 Mason and Jarosewich (1967).

e Mason (1963a).
NUMBER 3

The factors controlling the distribution of chromium

between chromite and pyroxene remain to be elucidated. The low content in the Mt. Egerton enstatite

reflects the highly reduced state of this meteorite, and

is in agreement with the microprobe data of Reid and

Cohen (1967).

Manganese: The data in Table 7 were obtained

partly by the microprobe, for concentrations above

1000 ppm, and by the mass spectrometer for lower

concentrations. The results show that in the ordinary

chondrites this element is present in approximately

equal amounts in olivine and pyroxene, at the 3000

ppm level. The low figure for the Mt. Egerton

enstatite is characteristic of this mineral from enstatite

achondrites and enstatite chondrites. Terrestrial minerals from the Gamperdown peridotite have lower

manganese contents than those from chondrites.

Cobalt: Over 99 percent of this element in stony

meteorites is contained in the nickel-iron, so even a

slight contamination of the other phases with metal

will add considerably to their cobalt content. This is

probably responsible for some of the erratic figures in

Table 8, especially the high content in Modoc phosphate, and the somewhat higher content in St. Severin

silicates compared to those from Modoc. Cobalt was

detected in all phases except the Mt. Egerton enstatite.

TABLE 7.—Manganese {ppm)

Meteorite Metal Troilite Olivine Ortho- Clino- Plagioclase Chromite Phosphate

pyroxene pyroxene

Bulk

Camperdown

Modoc

St. Severin...

Winona

Haraiya

Marjalahti...

Springwater.

Johnstown...

Mt. Egerton.

Soroti

2

<10

2

<10

150

290

1

 3, 600

i 3, 200

2,200

2,600

* 3, 600

1

 2, 900

1

 2, 000

3, 900

» 150

1

 600

i 2, 000

i 1, 900

i 1, 400

1

 7,400

230

220

300

320

3 6, 000

2

 5, 000

580

520

* 2, 600

« 2, 500

« 1. 940

860

1

 Microprobe analysis.

2

 Jarosewich (unpublished).

3 Bunch et al. (1967).

* Mason and Wiik (1967).

5

 Jarosewich and Mason (1969).

6 Mason and Jarosewich (1967).

7 Mason (1963b).

8 Mason (1963a).

» Reid and Bohen (1967).

Meteorite

Camperdown

Modoc

St. Severin

Winona. . . . •

Haraiya

Marjalahti

Springwater

Johnstown

Mt. Egerton

Sorot

Metal

i 10, 000

2

 12,000

Troilite

58

40

42

TABLE {

Olivine

210

25

45

7

24

3.—Cobalt

Orthopyroxene

50

7

19

3

11

n.d.

(Ppm)

Clinopyroxene

28

10

9

Plagioclase

1

6

1

1

Chromite

CO CO

CM CO

Phosphate

620

34

Bulk

1800

2

 400

3 400

1 Mason and Wiik (1967).

2

 Jarosewich and Mason (1969).

380-526 O—70 2

3

 Mason and Jarosewich (1967).
8 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

It is more concentrated in olivine than pyroxene,

which agrees with data from terrestrial minerals.

Terrestrial minerals, however, normally contain a considerably higher cobalt concentration than meteoritic

minerals, and this is illustrated by the figures for the

minerals from the Camperdown peridotite.

Nickel: The distribution of this element (Table 9)

closely resembles that of cobalt, and the same remarks concerning contamination problems apply. Both

troilite and olivine contain appreciable amounts of

nickel. The figures for troilite agree with unpublished

analyses of the same samples by E. Jarosewich: Modoc,

860 ppm; St. Severin, 760 ppm; Soroti, 510 ppm.

Pyroxene contains much less nickel than olivine. The

consistently higher figures for nickel in the pyroxene,

plagioclase, and chromite separates from St. Severin

suggest that these separates are slightly contaminated

with the metal phase. Nickel could not be measured

in the phosphate separates because of a concurrent

phosphorus line (2 x P31). Terrestrial olivine, orthopyroxene, and clinopyroxene from the Camperdown

peridotite show about ten times the nickel concentration of the corresponding meteoritic minerals.

Copper: Hey and Easton (1968) have recently

studied the distribution of this element in chondrites

by selective decomposition of the different phases.

They found 22-65 ppm in kamacite, 1610-2610 ppm

in taenite, 1-114 ppm in troilite, 17.8-41.5 ppm in

olivine, 6.0-22.3 ppm in pyroxene (plus plagioclase).

Our results (Table 10) are in good agreement with

these values, although the somewhat erratic figures for

troilite and chromite suggest the presence of sporadic

grains of native copper. The high figure for St. Severin

metal reflects the fact that the nickel-iron in this

TABLE 9.—Nickel {ppm)

Meteorite Metal. Troilite

(percent)

Olivine Ortho- Clino- Plagioclase Chromite Phosphate

pyroxene pyroxene

Bulk

Camperdown

Modoc

St. Severin. .

Winona

Haraiya

Marjalahti. .

Springwater.

Johnstown...

Mt. Egerton.

Soroti

14.9

26.8

820

910

2,000

230

290

34

110

630

46

190

34

* 10

n.d.

310

13

20

<20

74

27

<20

20 conflict

 J 13,000

410 conflict

 2 10,500

3 12, 000

570

1 Mason and Wiik (1967).

2

 Jarosewich and Mason (1969).

3

 Mason and Jarosewich (1967).

* Mason (1963a).

Meteorite

Camperdown

Modoc

St. Severin

Winona

Haraiya

Marjalahti

Springwater

Johnstown

Mt. Egerton

Soroti

Metal Troilite

620 220

1,900 64

130

TABLE

Olivine

7

14

14

3

4

10.—Copper (ppm)

Orthopyroxene

3

7

10

13

9

1

Clinopyroxene

4

8

35

Plagioclase

5

10

7

16

Chromite

460

21

Phosphate

52

20

Bulk

170

71
NUMBER 3

meteorite is entirely taenite, whereas that in Modoc is

a mixture of kamacite and taenite. Our figures for the

silicates are comparable with theirs, although we find

somewhat less in olivine than they did. Pallasite olivine

and achondrite orthopyroxene contain less copper than

these minerals in chondrites. Terrestrial olivine, orthopyroxene, and clinopyroxene from Camperdown contain less copper than these minerals from chondrites.

Zinc: The data are presented in Table 11. Zinc was

not detected in the metal phases. In the analyses of the

troilite the Zn6G line could not be utilized, because of

conflict with 2 x S33, and the Zn67 line was absent (an

isotope of low abundance); Nishimura and Sandell

(1964) report 10±5 ppm Zn in troilite from chondrites, which would be consistent with our data. Zinc

is distributed in all the oxidic phases. Chromite may

contain a high concentration, as in St. Severin; Bunch

et al. (1967) report about 1.1 percent ZnO in one

chondritic chromite, that from Pultusk. In the silicates

zinc is about equally concentrated in olivine and pyroxene, with comparatively little in plagioclase. Zinc is

very low in pallasite olivine, and in achondrite orthopyroxene.

Gallium: This element was measurable in all the

separates except the Mt. Egerton enstatite and the

Soroti troilite (Table 12). It is notable for being detectable in all phases, but is concentrated in the metal,

plagioclase, and chromite. However, the plagioclase in

Winona and especially Haraiya is notably depleted in

comparison to the chondrite plagioclases. The lower

content in metal from St. Severin may be related to

the somewhat higher degree of oxidation of this meteorite compared to Modoc. The figures obtained are

consistent with those reported by Moss et al. (1967)

and Fouche and Smales (1967) for other chondrites.

The concentrations in terrestrial minerals from the

Gamperdown peridotite are similar to those in the

meteoritic minerals.

TABLE 11.—^inc (ppm)

Meteorite Metal Troilite Olivine Ortho- Clino- Plagioclase Chromite Phosphate

pyroxene pyroxene

Bulk

Gamperdown

Modoc

St. Severin. .

Winona

Haraiya

Marjalahti. ..

Springwater..

Johnstown. . .

Mt. Egerton.

Soroti

n.d.

n.d.

n.d.

n.d.

19

20

19

3

5

6

17

14

48

5

n.d.

6

20

19

n.d.

3

3

5

5

1,

86

800

19

22

TABLE 12.—Gallium (ppm)

Meteorite Metal Troilite Olivine Ortho- Clino- Plagioclase Chromite Phosphate Bulk

pyroxene pyroxene

Camperdown

Modoc

St. Severin ..

Winona

Haraiya

Marjalahti ..

Springwater .

Johnstown . .

Mt. Egerton.

Soroti

22

10

6

5

0.8

2

2

0.6

1

1

2

2

1

1

n.d.

1

2

17

23

8

3

65

69

n.d.
10 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

Germanium: This element was found only in the

metal phase of the meteorites. Fouche and Smales

(1967) found 128 ppm in Modoc metal, and using this

figure as a standard we find 280 ppm in St. Severin

metal. Since the metal in St. Severin is about half as

abundant as in Modoc, the total germanium content

of each meteorite is approximately the same, about

9 ppm. Moss et al. (1967) found 122 ppm and 127 ppm

in the nickel-iron of the Barwell and Ohuma meteorites, which are hypersthene chondrites similar in

composition to Modoc. In the Camperdown minerals

germanium was not detected in the olivine, and was

present at about 2 ppm in the orthopyroxene and the

diopside.

Arsenic: Like germanium, this element has been detected only in the meteoritic nickel-iron; we found

25 ppm in Modoc metal, 43 ppm in St. Severin metal.

Both meteorites evidently contain about the same

amount of this element, but this is more highly concentrated in the smaller amount of metal in St. Severin.

Fouche and Smales (1967), by neutron activation, determined 20.4 ppm in Modoc metal, in good agreement

with our figure.

Selenium: This element is concentrated in the troilite, and has not been detected in other phases. The

concentration has not been measured because of the

lack of suitable standards, but using the average of

8 ppm for chondritic meteorites determined by

DuFresne (1960), the amount in the troilites is about

130 ppm.

Bromine: This element was detected in metal,

troilite, and phosphate separates, at about the 1 ppm

level (except for Modoc phosphate, which contained

on the order of 5-10 ppm).

Rubidium: As expected from crystallochemical considerations, essentially all the rubidium is contained in

the feldspar; the only separates in which this element

was detected were sodic plagioclase from Modoc

(28 ppm), St. Severin (5 ppm), and Winona (12

ppm). It was not detected in the calcic plagioclase

from Haraiya. It is remarkable that the level of Rb in

St. Severin feldspar is only about one-fifth that of

Modoc; however, the Rb content of the bulk meteorite

(0.8 ppm) is also much below the chondrite average.

Smales et al. (1964) have found that the rubidium content of different chondrites is notably erratic.

Strontium: The results reported in Table 13 show

that the plagioclase contains most of the strontium in

these meteorites, although this element is also enriched

in the phosphate separates. Pyroxene contains more

strontium than olivine. This element was not detected

in the metal or troilite separates.

Yttrium: Table 14 shows that yttrium, like the

lanthanides, is largely contained in the phosphate minerals. Diopside from Winona and pigeonite from

Haraiya show a concentration of this element. Otherwise, detectable amounts were found in orthopyroxene,

plagioclase, and in the troilite. The amounts in terrestrial orthopyroxene and diopside are somewhat

lower than in the meteoritic minerals.

Zirconium: From crystal chemistry considerations,

this element is unlikely to substitute readily for any of

the major cations. The mineral zircon (ZrSiO4) has

been observed in a few mesosiderites and one chondrite,

and sporadic grains of this mineral would readily account for the amount of zirconium (of the order of

10 ppm) in stony meteorites. The general consistency

of the data for individual minerals in Table 15, howTABLE 13.—Strontium {ppm)

Meteorite Metal Troilite Olivine Ortho- Clino- Plagioclase Chromite Phosphate Bulk

pyroxene pyroxene

Gamperdown

Modoc

St. Severin. .

Winona

Haraiya

Marjalahti. ..

Springwater .

Johnstown ..

Mt. Egerton .

Soroti

n.d.

n.d.

n.d.

n.d.

1

0.4

0.9

0.5

0.4

4

4

5

5

2

2

280

14

6

75

73

73

130

8

6

87

62

11

10

n.d.
NUMBER 3 11

TABLE \4.—Tttrium (ppm)

Meteorite Metal Troilite Olivine Ortho- Clino- Plagioclase Ckromite Phosphate

pyroxene pyroxene

Bulk

Camperdown

Modoc

St. Severin. .

Winona

Haraiya

Marjalahti...

Springwater.

Johnstown...

Mt. Egerton.

Soroti

n.d.

n.d.

1

1

n.d.

n.d.

n.d.

n.d.

n.d.

0.5

0.8

2

1

1

n.d.

9

23

15

n.d.

n.d.

160 i 2. 07

210 2

0.5

Schmitt et al. (1964).

TABLE 15.—Zirconium (ppm)

Meteorite Metal Troilite Olivine Ortho- Clino- Plagioclase Chromite Phosphate Bulk

pyroxene pyroxene

Gamperdown

Modoc

St. Severin. .

Winona

Haraiya

Marjalahti...

Springwater.

Johnstown...

Mt. Egerton.

Soroti

n.d.

n.d.

3

3

1

n.d.

n.d.

n.d.

n.d.

3

6

22

6

2

n.d.

60

90

29

650

18

ever, suggests that sporadic zircon is not responsible

for the distribution pattern (except probably for the

very high figure in Modoc phosphate, and possibly for

the Winona diopside and St. Severin orthopyroxene).

Most of the zirconium appears to be present in the

calcium-rich clinopyroxene, a trend followed also by

the terrestrial minerals in the Camperdown peridotite.

The presence of 3 ppm in troilite indicates minor chalcophile affinity for zirconium, as has been suggested

by Setser and Ehmann (1964); they recorded 6.3 ppm

in troilite from the Canyon Diablo iron.

Niobium: The concentration of niobium in ordinary

chondrites is not well known, but is probably of the

order of 1 ppm. We have measured 1-2 ppm in meteoritrc chromite, phosphate, and clinopyroxene, and

detected this element (< 1 ppm) in troilite, olivine,

orthopyroxene, and plagioclase. The Camperdown

minerals contain niobium at approximately the same

concentration as the corresponding meteoritic minerals.

Molybdenum: This element was observed in metal

and troilite separates, with somewhat greater concentration in the metal; it was not observed in other

phases. Results obtained (in ppm) are: Modoc metal,

7; Modoc troilite, 3; St. Severin metal, 10; St. Severin

troilite, 3; Soroti troilite, 3. These figures are consistent with the data of Kuroda and Sandell (1954),

although their results are generally somewhat larger.

Ruthenium, rhodium, palladium: These three geochemically coherent elements were prominently

present in spectra of the metal phases only. Previous

suggestions that ruthenium and possibly palladium

show some chalcophile affinity in meteorites were not

borne out; neither element was detected in troilite.

The amounts of these elements in the metal phases
12 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

could not be evaluated because of the lack of suitable

standards. Nichiporuk and Brown (1965) reported the

following average amounts in chondrite metal: Ru,

6 ppm; Rh, 1 ppm; Pd, 4 ppm. Fouche and Smales

(1967) report 6.87 ppm in Modoc metal.

Silver: This element was just visible in spectra of

the troilites, but absent from those of other phases.

Cadmium: This element was not detected.

Indium: This element was not detected.

Tin: Tin was detected only in the metal phase;

2 ppm in Modoc metal, 8 ppm in St. Severin metal.

This is in agreement with earlier work by Onishi and

Sandell (1957) and Shima (1964), who found that

this element is essentially confined to the magnetic

(i.e., metallic) fraction of chondritic meteorites.

Antimony: This element was found at about 1 ppm

in the metal phase only. Fouche and Smales (1967)

record 0.72 ppm in metal from Modoc.

Tellurium: Lines of tellurium are visible in spectra

of the metal and troilite, and are absent in spectra

of the other phases. The concentration is approximately the same in the metal and in the troilite. This

is contrary to the results of Goles and Anders (1962)

on iron meteorites; they record 5 ppm in Canyon

Diablo troilite, 0.09 ppm in the metal; and 1.7 ppm

in Toluca troilite, 0.05 ppm in the metal. The equilibrium conditions in iron meteorites, however, may

be considerably different for this element from those

in the chondrites.

Iodine: Since methylene iodide was used in the

mineral separations (except for the Soroti troilite)

the iodine line observed in these separates can be

ascribed to contamination. Iodine was not detected in

the Soroti troilite. Goles and Anders (1962) record

that this element is chalcophile in iron meteorites;

they found 0.06 ppm in Canyon Diablo troilite, 0.03

ppm in the metal, and 1 ppm in Toluca troilite, 0.25

ppm in the metal.

Cesium: This element was detected in plagioclase

from Modoc (0.4 ppm), St. Severin (0.3 ppm), and

Winona (0.4 ppm).

Barium: The results (Table 16) show, as might be

predicted, that most of the barium in a stony meteorite

is contained in the feldspar. The phosphate contains

a moderate amount, as does the Winona diopside.

The other minerals contain about 1-3 ppm barium,

except the metal, in which this element was not

detected.

Lanthanides: The data for the lanthanides (here

considered to comprise the elements La-Lu) are given

in Table 17 and illustrated in Figure 1. In the

chondrites (Modoc and St. Severin) these elements

are highly enriched in the phosphate minerals, and

are at concentrations of less than about 0.2 ppm in

the other phases (except europium, which is present

in the feldspar at about 1 ppm). Comparison of the

data for the phosphate minerals with those for a

chondrite composite (Haskin et al., 1968) shows that

the phosphates account for almost 100 percent of the

lighter lanthanides (La-Sm), and 50 percent or more

of the heavier lanthanides (Gd-Yb). The amounts

unaccounted for in the phosphates are probably contained in the pyroxenes, which consistently show

an enrichment in the heavy relative to the light

lanthanides.

The Haraiya separates, calcic plagioclase and

TABLE 16.—Barium {ppm)

Meteorite Metal Troilite Olivine Ortho- Clino- Plagioclase Chromite Phosphate

pyroxene pyroxene

Bulk

Camperdown

Modoc

St. Severin. .

Winona

Haraiya

Marjalahti...

Springwater .

Johnstown...

Mt. Egerton.

Soroti

n.d.

n.d.

<0. 5

0.8

0.9

3

0.6

1

42

40

51

72

2

0.8

11

16

13.8

6

1

 Reed et al. (1960).
NUMBER 3 13

TABLE 17.—Lanthanide elements (ppm)

Element

La

Ce

Pr

Nd

Sm

Eu. .

Gd

Tb . .

Dy

Ho

Er

Tm

Yb. . .

Modoc

Phosphate

51

120

17

65

27

2.5

30

4.4

34

8.6

19

2.4

18

St. Severin

Phosphate

64

130

25

100

34

2.5

50

6.8

49

12

26

3.2

25

Feldspar

0.94

0.84

0.093

0.30

<0. 15

0.51

<0. 13

<0. 03

<0. 14

<0. 04

<0. 10

<0. 02

<0. 10

Winona

Enstatite

0. 13

0.33

0.080

0.41

<0. 2

<0. 04

0. 34

0.040

0.33

0.090

0.24

0.04

0.33

Diopside

3.0

11

2. 1

11

5. 1

0.085

7.2

0.83

6.5

1.6

3. 1

0.32

2.4

Haraiya

Feldspar

1.4

2. 1

0.22

0.82

0.30

0.66

0.60

0.06

0.43

0.075

0.20

<0. 04

0.22

Pyroxene

0.25

0.86

0. 19

0.95

0.51

<0. 02

0.80

0. 12

1. 1

0. 31

0.85

0. 13

1.0

Angra

dos

Reis

8. 3

19

3. 7

17

5.5

1.6

7.6

1. 1

8.7

2.0

4.6

0.56

4.2

pigeonite, show the preference of the lighter lanthanides and europium for the plagioclase and that of

the heavier lanthanides for the clinopyroxene, a

phenomenon already estabilshed for the Juvinas

eucrite (Philpotts et al., 1967) and for terrestrial

plagioclase/pyroxene pairs. The Winona separates

(plagioclase, enstatite, and diopside) show the same

trend but with a larger separation of their lanthanide

patterns. The considerable enrichment of all the lanthanides in diopside relative to enstatite (and relative

to Haraiya pigeonite) is evidently related to the

crystal structure of diopside, with a lattice position

which readily accommodates calcium and ions of

similar size, such as the lanthanides. Although the

lanthanides are highly concentrated in diopside relative to enstatite, these two minerals account for comparable amounts of each element in the meteorite as

a whole, since the enstatite is much more abundant

(40 percent) than the diopside (2.5 percent).

The Angra dos Reis meteorite, which consists almost entirely of augite, has a lanthanide pattern that

is highly enriched and very little fractionated when

compared with that of chondritic meteorites. Schnetzler and Philpotts (1969) report comparable results for

some of these elements. Angra dos Reis show only slight

improverishment in europium, unlike the other pyroxene separates. This suggests either that the conditions

of crystallization were such that no Eu2 could form and

that the element behaved as any other triply charged

lanthanide, or that there was no competing phase, such

as plagioclase, that would capture any Eu2 were it

present.

Hafnium: As might be predicted, hafnium follows

the pattern of zirconium, being detected only in those

samples relatively rich in this element—St. Severin

orthopyroxene and phosphate, Modoc phosphate, and

clinopyroxene from Winona, Haraiya, and Camperdown peridotite. The concentration in Modoc phosphate is 18 ppm, in Winona diopside 4 ppm; in the

other samples the concentration was too low for accurate measurement.

Tantalum: In view of its low abundance, it is unlikely that this element could be detected in any of the

meteorite mineral separates. In addition, the tantalum

mountings of the spark source are a possible contaminant.

Tungsten, rhenium: These elements were detectable

in the metal phases, but were not observed in any of

the other separates. Fouche and Smales (1967) report

0.52 ppm Re in Modoc metal.

Osmium, indium, platinum, gold: The lines of these

elements are prominent in the spectra of the nickeliron, but are absent from those of the other separates.

Suitable standards for evaluating the amounts were not

available, but the results are consistent with the figures

given for chondrite metal by other investigators: Ir,

2.8 ppm (Nichiporuk and Brown, 1965) ; Pt, 8.5 ppm

(Nichiporuk and Brown, 1965); Au, 1.2 ppm (Baedecker and Ehmann, 1965). Fouche and Smales

(1967) report 2.11 ppm Au in Modoc metal.
14 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

La Ce Pr Tm Yb

FIGURE 1.—Chondrite-normalized lanthanide concentrations in meteorite minerals (broken

lines indicate maximum values) : 1, St. Severin phosphate; 2, Modoc phosphate; 3, Angra dos

Reis; 4, Winona diopside; 5, Haraiya plagioclase; 6, Winona plagioclase; 7, Haraiya pigeonite;

8, Winona enstatite. (Note added in proof: The points for Gd are systematically low, the values

used being one-half those given for this element in Table 17.)
NUMBER 3 15

Mercury: This element was not detected.

Thallium: This element was not detected, except in

those separates for which Glerici solution had been

used as a separating medium, thereby introducing

thallium as a contaminant.

Lead: This element was detected in both metal and

troilite separates from Modoc, with the troilite having

the greater concentration. The metal and troilite separates from St. Severin also showed lead, but since these

had been treated with Clerici solution, this element

may have been thereby introduced. Lead is present in

Soroti troilite at a concentration of 4 ppm. Lead was

also detected in Haraiya and Winona feldspar.

Bismuth: This element was not detected in any

separates.

Thorium: Only the phosphate separates contain detectable amounts of this element, Modoc phosphate

having 7 ppm, St. Severin phosphate 6 ppm.

Uranium: This element was barely detectable in St.

Severin phosphate, and was measured at 4 ppm in the

Modoc phosphate. The latter figure seems somewhat

high, in view of the known Th: U ratio.

Summary

Although the number of meteorites examined in this

research is small, they are representative of the major

classes of stony meteorites, except the enstatite and

carbonaceous chondrites. The following generalizations

regarding the distribution of minor and trace elements

in specific minerals, therefore, may be tentatively

offered.

Nickel-iron: The metal phase in an ordinary chondrite contains over 99 percent of the nickel and cobalt

in the meteorite, and probably at least 90 percent of the

following elements: Ge, As, Ru, Rh, Pd, Sn, Sb, W,

Re, Os, Ir, Pt, Au. Copper and gallium show both

siderophile and lithophile affinity, and molybdenum

and tellurium show both siderophile and chalcophile

affinity.

Troilite: It is noteworthy that the only measured

element which is entirely chalcophile, appearing in

troilite but in no other phase, is selenium. Silver, cadmium, indium, thallium, and lead are probably concentrated in troilite, although their abundance level

was too low for measurement. Elements present in

troilite at the 100-1000 ppm level are Ni, Cr, Mn, and

Cu; at the 10-100 ppm level Cl, Sc, Ti, and Co; at the

1-10 ppm level V, Zn, Ga, Y, Zr, Mo, and Ba.

Olivine: This mineral does not readily accept minor

and trace elements into its structure. Of the elements

studied only Mn is present in meteoritic olivine in notable amounts (2000-3000 ppm). Meteoritic olivine

contains more Ni and Co than other meteoritic silicates, but the concentration of these elements is about

an order of magnitude lower than in terrestrial olivine

such as that in the Camperdown peridotite. Chondritic

olivine contains about 100-200 ppm Ti and about 300

ppm Cr; it contains about 20 ppm Zn, which may

represent about half the zinc in the meteorite.

Pyroxenes: Apart from Ni and Co, which are preferentially accepted in olivine, many of the minor and

trace elements with lithophile affinity tend to concentrate in the pyroxenes. This is particularly true of the

transition elements scandium through manganese. In

general, the concentration in clinopyroxene is greater

than in orthopyroxene. In chondrites the major part

of the lanthanides (and yttrium) are contained in the

phosphate phases, but detectable amounts are present

in the pyroxenes.

Plagioclase: As might be predicted, the sodic plagioclase of chondrites contains most of the Rb, Cs, Sr, and

Ba in these meteorites. It also contains appreciable

amounts of the Sc and Ga.

Chromite: Apart from chromium, this mineral also

concentrates vanadium, and to a lesser extent titanium,

manganese, and gallium.

Phosphate: The phosphate minerals in chondritic

meteorites account for most of the lanthanides, yttrium,

uranium, and thorium in these meteorites. If apatite is

present, it will contain essential amounts of fluorine and

chlorine. Other elements enriched in the phosphate

minerals include Sc, Sr, Zr, Ba, and Hf.

Acknowledgments

I am greatly indebted to the Australian National University for an appointment as Visiting Research Fellow

and for the use of the equipment and facilities of the

Department of Geophysics and Geochemistry. I would

also like to express my thanks to the John Simon Guggenheim Memorial Foundation for the award of a

fellowship to work in Australia, and to the Smithsonian

Research Foundation for a grant toward laboratory

expenses. Mr. J. Nelen provided some microprobe

analyses, and Mr. E. Jarosewich some wet-chemical

analyses, which are gratefully acknowledged. Dr. R. Fudali and Dr. L. Walter reviewed the manuscript, and

their critical comments contributed greatly to the final

version. [Brian Mason]
16 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

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Bunch, T. E., K. Keil, and K. G. Snetsinger

1967. Ghromite Composition in Relation to Chemistry

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Corlett, M., and P. H. Ribbe

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317-332.

DuFresne, A.

1960. Selenium and Tellurium in Meteorites. Geochimica et Cosmochimica Ada, 20:141-148.

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