Chemical Geology - Elsevier Publishing Company, Amsterdam Printed in The Netherlands

CHROMIUM AND MANGANESE IN CHONDRITES

ANN M. YATES 1, STANFORD L. TACKETT 2 and CARLETON B. MOORE 3

1Chemalytics, Inc., Tempe, Ariz. (U.S.A.) 2Department of Chemistry, Indiana University of Pennsylvania, Indiana, Pa. (U.S.A.) 3Center for Meteorite Studies, Arizona State University, Tempe, Ariz. (U.S.A.)

(Received February 16, 1968)

SUMMARY

C h r o m i u m and m a n g a n e s e were d e t e r m i n e d in 15 L group, 12 H group and eight c a r b o n a c e o u s chondr i t e s u s ing an X - r a y f l u o r e s c e n c e technique. Although the g r o s s f r a c t i ona t i on of c h r o m i u m be tween H and L group chon- d r i t e s ind ica ted in Urey and C r a i g ' s (1953) compi la t ion of s u p e r i o r a n a l y s e s was not found in this work, the L group a p p e a r s to be deple ted in c h r o m i u m . The d e t e r m i n e d r a t i o s for M n / C r a r e H group 0.57 + 0.02, L group 0.63 + 0.03; abundances r e l a t i v e to s i l i con a r e ca l cu la t ed for the chondr i t e s ana lyzed .

A d i r ec t r e l a t i o n s h i p is found be tween c h r o m i u m and m a n g a n e s e in both H and L group chondr i t e s , but an i n v e r s e r e l a t i o n s h i p be tween these two e l e m e n t s is ind ica ted for the c a r b o n a c e o u s chondr i t e s .

INTRODUCTION

It has often been diff icul t to c o m p a r e e l e m e n t a l abundances within and among chondr i t e g roups due to appa ren t v a r i a b i l i t i e s in ana ly t i c a l and s a m p l e qual i ty . This is p a r t i c u l a r l y t rue with r e s p e c t to the m i n o r and t r a c e e l e - m e n t s in chondr i t e s g e n e r a l l y d e t e r m i n e d by c l a s s i c a l ana ly t i ca l t echn iques . Although the g e n e r a l i z a t i o n has been made that chondr i t e s a r e somewhat cons tan t in compos i t ion , t he r e a r e notable excep t ions to this , p a r t i c u l a r l y in the case of i r on by which high and low i r o n groups of chondr i t e s may be d i s t i n g u i s h e d (Urey and Cra ig , 1953). A h r e n s (1964) has a l so poin ted out v a r i a t i o n s in the s i l i con to m a g n e s i u m r a t i o s be tween the c a r bona c e ous , o r d i n a r y and ens t a t i t e chond r i t e s but e a r l i e r (Ahrens et al . , 1960) had noted a u n i f o r m i t y of l i thophi le e l e m e n t s in chondr i t e s . Moore and Brown (1962) noted a s t r i k i n g u n i f o r m i t y in the m a n g a n e s e to t i t a n i u m r a t i o even though m a n g a n e s e is often found p a r t i a l l y in the sul f ide phase in m e t e o r i t e s . Recent work r ev i ewed by L a r i m e r and A n d e r s (1967) a l so ind ica te s d i r e c t r e l a t i o n - sh ips be tween such geochemica l l y d i v e r s e e l e m e n t s such as c e s i um, zinc and ca rbon .

Th i s s tudy was u n d e r t a k e n to examine the d i s t r i b u t i o n and f r a c t i o n a - t ion of c h r o m i u m . C h r o m i u m l ike m a n g a n e s e and t i t a n i u m is a m i n o r e l e - men t which often shows g r ea t v a r i a t i o n in the s u p e r i o r chondr i t e a n a l y s e s l i s t ed by Urey and Cra ig (1953). In th is inves t iga t ion , c h r o m i u m and m a n g a n e s e were d e t e r m i n e d in 15 L group and 12 H group chondr i t e s u s i ng

Chem. Geol., 3 (1968) 313-322 313

an X - r a y f l u o r e s c e n c e technique. In addi t ion to the o r d i n a r y chondr i t e s , eight c a r b o n a c e o u s chondr i t e s were checked at the r e que s t of H.B. Wiik. The powders ana lyzed were sp l i t s f rom his e a r l i e r wet a n a l y s e s of those s ame m e t e o r i t e s . This s e r v e d two pu rpose s : (1) Since the s a m p l i n g p r ob l e m is m i n i m a l in this group, the va lues obta ined by XRF could be c o m p a r e d with those ob ta ined by conven t iona l wet chemica l methods with conf idence; (2) c o m p a r i s o n of M n / C r va lues of this group with those of the H and L group chondr i t e s could be made.

ME~IHOD Ol ~ ANALYSIS

Preparation of standards

Standard s a m p l e s of app rox ima te chondr i te compos i t ion were p r e p a r e d by weighing out app rop r i a t e amoun t s of r eagen t g rade oxides of the e l emen t s . Approx ima te ly 250 mg of each of these s a m p l e s , 25 mg of Nb20 5 and 1 g of L i 2 B 4 0 7 were weighed out a c c u r a t e l y , mixed thoroughly to a t ta in homo- genei ty , and fused in covered g raph i te c r u c i b l e s to f o r m g lass beads . Each of these beads was then ground to a fine powder and a por t ion of each mixed with s t e a r i c ac id in the r a t io of 5:1 by weight. These m i x t u r e s were then p r e s s e d into fiat s ample pe l l e t s to be used in se t t ing up c a l i b r a t i o n c u r v e s for the ana lyse s .

Preparation of chondritic samples

Since chondr i t e s u sua l ly conta in an app rec i a b l e amount of me ta l l i c phase in addi t ion to the s i l i c a t e and sul f ide phases , the p r ob l e m of s a m p l i n g could not be ignored. P r e l i m i n a r y a n a l y s e s of s e v e r a l one g r a m s a m p l e s f r o m the Leedey chondr i t e gave va lues which app rox ima ted a n o r m a l d i s t r i b u t i o n with a r e l a t i v e s t a n d a r d devia t ion of about 6%. The d e t e r m i n e d va lues toge ther with those d e t e r m i n e d by wet a n a l y s i s and the X - r a y f l u o r e s c e n c e r e s u l t s of Nichiporuk et al. (1967) a r e given in Table I. A s a m p l e s ize of 1 g, t he re fo re , was deemed to be suf f ic ien t ly " r e p r e s e n t a t i v e . "

Taking, then, e i t he r a one g r a m sample (without fus ion c rus t ) of a chondr i t e , or a por t ion of the powder f r o m a p r e v i o u s l y c r u she d l a r g e r s amp le , pe l l e t s we re p r e p a r e d in the s a m e m a n n e r as for the s t anda rds . When an in i t i a l 1-g s a m p l e was used, dupl ica te pe l l e t s were p r e pa r e d ; in the o ther cases , a s ing le pe l le t was p r e p a r e d for each me teo r i t e .

Inslru~,l e~talion

A Gene ra l E l e c t r i c XRD-5 X - r a y f l u o r e s c e n c e uni t was u sed for the ana ly se s . The p r i m a r y r ad i a t i on was p rov ided by a Machle t t AEG-50S tungs ten t a rge t X - r a y tube ope ra t ed at 50 kV, 16 mA. A l i th ium f luor ide ana lyz ing c r y s t a l and a ~4 SPG flow p r o p o r t i o n a l coun te r tube (opera ted with a con t inuous flow of PR gas as r e c o m m e n d e d by the m a n u f a c t u r e r ) were a l so used. Since the s e c o n d a r y r ad i a t i on a r i s i n g f rom the e l e m e n t s be ing ana lyzed was of suf f ic ien t ly high ene rgy that l i t t le abso rp t i on by the a i r o c c u r r e d , an a i r path was u sed in the ana lys i s .

314 Chem. Geol., 3 (1968) 313-322

TABLE I

Ana lys i s of Leedey, Oklahoma chondr i t e

Sample Number I P e r c e n t Cr P e r c e n t Mn

(A) 1 0.401 0.258 0.400 0.257

(A) 2 0.365 0.228 0.361 0.226

(B) 1 0.398 0.240 0.405 0.243

(B) 2 0.390 0.237 0.396 0.240

(C) 1 0.351 0.237 0.347 0.230

(C) 2 0.344 0.236 0.348 0.236

(D) 1 0.362 0.243 0.356 0.240

:D) 2 0.354 0.235 0.357 0.239

(E) 1 0.408 0.261 0.417 0.265

(E) 2 0.368 0.232 0.373 0.232

Wet Chemica l Method 2 0.362 0.260

Nichiporuk et al. (1967) 0.35 0.27

1A, B, C, D, E r e p r e s e n t the five in i t ia l 1 g s am p l e s t aken for ana lys i s . Af ter c ru sh ing each to a powder, two s a m p l e s , 1 and 2 were taken f r o m each. These were t r e a t e d in the m a n n e r d e s c r i b e d above. The dupl ica te va lues of p e r c e n t r e p r e s e n t two m e a s u r e - m e n t s on the s ame sample pel le t . 2A.D. Maynes and E. J a r o s e w i e h , unpubl i shed data.

Experin~e~ztal .zeasurernents

U s i n g t h e p r e p a r e d s t a n d a r d s a m p l e s , c a l i b r a t i o n c u r v e s w e r e s e t up f o r c h r o m i u m a n d m a n g a n e s e b y p l o t t i n g t h e i n t e n s i t y r a t i o ( Ime ta l / I i~b ) v e r s u s t h e w e i g h t r a t i o (Wmeta 1 / W N b ) f o r e a c h s a m p l e . T h e s l o p e a n d i n t e r . c e p t of t h e b e s t s t r a i g h t l i n e r e p r e s e n t i n g t h e s e p o i n t s w e r e d e t e r m i n e d u s i n g a l e a s t s q u a r e s a n a l y s i s . E m p l o y i n g e q . 1 , t h e v a l u e s of t h e s l o p e a n d i n t e r c e p t of t h e c a l i b r a t i o n l i n e f o r e a c h of t h e e l e m e n t s :

Ime ta l i n t e r c e p t INb x 100 = % m e t a l (1)

s l o p e Wsam pl e WNb205

a n d t h e m e a s u r e d i n t e n s i t y r a t i o f o r e a c h s a m p l e , t h e p e r c e n t a g e s of c h r o m i u m a n d m a n g a n e s e w e r e d e t e r m i n e d f o r e a c h of t h e c h o n d r i t i c s a m p l e s .

Chem. Geol. , 3 (1968} 313-322 315

RESULTS

The p e r c e n t a g e s of c h r o m i u m and m a n g a n e s e in 35 chondr i t e s (8 c a r - b o n a c e o u s , 15 L group and 12 H group) are g iven in Tabl.e II. A l so g iven are the v a l u e s d e t e r m i n e d by Nichiporuk et al. (1967) u s i n g X - r a y f l u o r e s - cence s p e c t r o s c o p y .

The m e a n s , Yc, and standard dev ia t ions , s , of th e se p e r c e n t a g e s in each

TABLE II

C h r o m i u m and m a n g a n e s e con ten t s

C h r o m i u m M a n g a n e s e

Nich iporuk et al. (1967) th i s w o r k (%) (%)

Nich iporuk ct al. (1967) th i s work (% (%)

C a r b o n a c e o u s I Orguc i l 0.30

II Cold Bokkeveld Mighei M u r r a y 0.30 S ta ro j e B o r i s k i n o

III K a r o o n d a Mokoia 0.34 W a r r e n t o n

L g roup Alf iane l lo 0.32 B ju rbS le 0.34 B r u d e r h e i m 0.30 Chantonnay Colby, W i s c o n s i n D h u r m s a l a E r g h e o F a r m i n g t o n 0.32 Ho lb rook 0.32 K i s v a r s a n y K u t t i p p u r a m 0.30 Leedey 0.35 Modoc 0.33 New Conco rd 0.34 N y i r a b r a n y

H g roup Al legan 0.33 A r c h i e 0.32 B e a r d s l e y 0.33 Dokachi 0.34 H e s s l e Kesen 0.35 M e r u a 0.35 P a n t a r 0.32 P l a inv i ew 0.34 R i c h a r d t o n 0.32 R o s e City Sal ine

0.27 0.23 0.17

0.30 0.14 0.31 0.14 0.31 0.176 0.14 0.30 0.15

0.38 0.12 0.34 0.151 0.11 0.38 0.15

0.42 0.29 0.26 0.38 0.30 0.25 0.34 0.27 0.24 0.40 0.23 0.38 0.24 0.34 0.26 0.23 0.40 0.21 0.34 0.28 0.21 0.37 0.27 0.23 0.33 0.21 0.38 0.28 0.23 0.38 0.27 0.24 0.37 0.28 0.23 0.39 0.28 0.24 0.37 0.24

0.37 0.24 0.23 0.41 0.23 0.23 0.37 0.25 0.21 0.41 0.23 0.24 0.40 0.2'3 0.41 0.24 0.22 0.36 0.24 0.21 0.39 0.24 0.22 0.36 0.25 0.21 0.39 0.24 0.22 0.39 0.22 0.39 0.22

316 Chem. Geol . , 3 (1968) 313-322

TABLE III

Compar i son of values (in percen tages) with those of other worke r s 1

Wiik (1956) Greenland and Nichiporuk This work Lover ing (1965) et al. (1967)

Chromium Cc I 0.22 _+ 0.01

II 0.30 +_ 0.05 III 0.35 + 0.04

L group 0.37 + 0.06 H group 0.32 + 0.11

Manganese Cc I 0.18 + 0.01

II 0.16 + 0.02 III 0.16 i 0.01

L group 0.26 + 0.02 H group 0.24 + 0.04

(3) 0.220 (1) 0.30 0.27 (1) (10) 0.31 i 0.01 (3) 0.30 + 0.00 (4) (8) 0.2800 (3;4) 0.34 i 0.01 (4) 0.37 *_ 0.02 (3) (21) 0.3284 ! 0.0704 (31) 0.32 i 0.02 (30) 0.37 + 0.03 (15) (11) 0.2636 + 0.0662 (8) 0.31 ± 0.02 (27) 0.39 + 0.02 (12)

0.1810 0.23 0.17 0.177 +_ 0.001 0.14 L 0.00

0.1420 0.150 k 0.011 0.12 ± 0.02 0.2560 _+ 0.0259 0.27 + 0.01 0.23 ± 0.01 0.2228 + 0.0203 0.24 i 0.01 0.22 * 0.01

1The number s in p a r e n t h e s e s indicate the number of s amples analyzed.

TABLE IV

99% confidence in te rva l s for ch romium and manganese in chondri te groups

Chromium Manganese

Cc II 0.30 + 0.01 0.14 + 0.01 III 0.37 _+ 0.09 0.12 +_ 0.08 L 0.37 _+ 0.02 0.23 _+ 0.01 H 0.39 +_ 0.01 0.22 _+ 0.01

of t he c h o n d r i t i c t y p e s a r e c o m p a r e d in T a b l e III w i t h v a l u e s d e t e r m i n e d by o t h e r w o r k e r s . T h e e x p e r i m e n t a l v a l u e s f o r t he m a n g a n e s e c o n t e n t s of the L g r o u p a n d the H g r o u p c h o n d r i t e s m a y a l s o be c o m p a r e d w i t h t h o s e of M o o r e a n d B r o w n (1962) who r e p o r t e d v a l u e s of 0 .270 + 0.022 and 0.253 + 0.030% , r e s p e c t i v e l y , f o r t h e s e two g r o u p s . The i n t e r v a l s w i t h i n w h i c h the m e a n , p , of t h e p o p u l a t i o n s h o u l d l i e a r e g i v e n , a t t he 99% c o n f i d e n c e l e v e l , in T a b l e IV a n d s h o w n in F i g . 1 .

T h e c o n f i d e n c e i n t e r v a l s f o r t h e p e r c e n t a g e s of c h r o m i u m in the L g r o u p a n d H g r o u p c h o n d r i t e s o v e r l a p to s o m e e x t e n t so t ha t the t r u e m e a n , p , m a y b e t h e s a m e f o r b o t h g r o u p s . T h e i n t e r v a l f o r the t y p e II c a r b o n a c e o u s c h o n d r i t e s , h o w e v e r , i s s i g n i f i c a n t l y d i f f e r e n t f r o m e i t h e r .

T h e s a m e s t a t e m e n t s h o l d f o r t h e m a n g a n e s e c o n t e n t s . P l o t s of c h r o m i u m vs . m a n g a n e s e a r e g i v e n in F i g . 2 - 4 f o r e a c h of the

t h r e e m a j o r g r o u p s . It i s i n t e r e s t i n g to n o t e t h a t f o r t h e two o r d i n a r y c h o n - d r i t e g r o u p s , a d i r e c t r e l a t i o n s h i p b e t w e e n the two e l e m e n t s i s i n d i c a t e d w h i l e f o r t he c a r b o n a c e o u s c h o n d r i t e s , an u n e x p e c t e d i n v e r s e r e l a t i o n s h i p a p p e a r s to be p r e s e n t . In e a c h of t h e f i g u r e s , t he b e s t s t r a i g h t l i ne t h r o u g h t h e p o i n t s a s c a l c u l a t e d u s i n g t h e m e t h o d of l e a s t s q u a r e s h a s b e e n p l o t t e d . T h e s e l i n e s s u p p o r t t he c o r r e l a t i o n s i n d i c a t e d a b o v e but a c a l c u l a t e d v a l u e of r = - 0 . 5 f o r t h e P e a r s o n - p r o d u c t - m o m e n t c o e f f i c i e n t of c o r r e l a t i o n f o r t h e c a r b o n a c e o u s c h o n d r i t e s i n d i c a t e s t h a t t he c o r r e l a t i o n i s a r e l a t i v e l y

Chem. Geol., 3 {1968) 313-322 317

weak one. The 95% conf idence i n t e r v a l fo r r = 0 .3-0.87. Ca lcu la t ion of the abundance r a t i o s ( M n / C r ) fo r the m e t e o r i t e s in each

of the chondr i t e g roups g ive s the va lues found in Tab le V for the conf idence i n t e r v a l s at the 99% leve l . T h e s e va lues ind ica te that, s t a t i s t i c a l l y , the m a n g a n e s e to c h r o m i u m r a t i o s a r e s ign i f i can t ly d i f fe ren t in c a r b o n a c e o u s , L and H groups .

Tab le VI g ive s the a v e r a g e a t o m i c abundances and the s t anda rd d e v i a - t ion fo r each group r e l a t i v e to 106 a t o m s of s i l i con .

F r o m the va lues tabula ted , it a p p e a r s that the L group chond r i t e s have been dep le ted in c h r o m i u m with r e s p e c t to the o the r chondr i t e groups . This is suppor t ed by the h igher va lue of M n / C r fo r the L group chondr i t e s .

DISCUSSION

U r e y and C r a i g (1953) ind ica ted a m a j o r d i f f e r e n c e be tween the c h r o m i u m abundances in H and L group o r d i n a r y chondr i t e s . On the b a s i s of this apparen t f r ac t i ona t i on , one of the au tho r s deve loped an unpubl i shed chondr i t e f r a c t i ona t i on mode l ba sed upon c r y s t a l f ie ld s t ab i l i z a t i on e n e r g i e s (Yates , 1966). The data p r e s e n t e d in th is p a p e r ind ica te that c h r o m i u m does not exhibi t the g r o s s f r a c t i ona t i on ind ica ted in U r e y and C r a i g ' s compi la t ion . F u r t h e r de t a i l ed work wil l be n e c e s s a r y to p rove s t a t i s t i c a l l y whe the r the a t o m i c abundances of c h r o m i u m do show a s m a l l f r ac t iona t ion . The c h r o m i u m

I ICe II

I Cc Ill

1 I L

I Z 3 .

i o~6 o;o . . . . . . . . . 0.34 0.38 0.42 OA6 0.50 A °/°Cr

I [ cc u

0.02

I ] Cc I[I

V-'IL

[ ]H

0. 6 0.10 0.14 0.18 022 °& M n

Fig.1. Confidence intervals. A. Chromium. B. Manganese.

318 Chem. Geol., 3 (1968) 313-322

o.4o[ °/oCr

0.38 ~ 0 6 0 8

0.3(~

0.34 07 ~

0.32

0.30 02 O5

0.28

0.26 0.10 0.12 0.14 0.16 0.18

% M n

Fig.2. C h r o m i u m - m a n g a n e s e r e l a t i onsh ip in ca rbonaceous chondr i t e s . 1 = Orguei l ; 2 = Cold Bokkeveld; 3 = Mighei; 4 = Mur r a y ; 5 = S ta ro je Bor i sk ino ; 6 = Karoonda; 7 = Mokoia; 8 = War ren ton .

d i s t r i b u t i o n in o r d i n a r y chondr i t e s a p p e a r s to follow a d i r ec t r e l a t ion to m a n g a n e s e . This is ana logous to the r e l a t i on be tween m a n g a n e s e and t i t an ium o b s e r v e d by Moore and Brown (1962). When one is concen t r a t ed , the o thers follow.

The nega t ive c o r r e l a t i o n o b s e r v e d in the ca rbonaceous chondr i t e s is a d i f fe ren t p rob l em.

A nega t ive c o r r e l a t i o n is r a t h e r diff icul t to u n d e r s t a n d in t e r m s of to ta l e l e m e n t a l abundances for it g e n e r a l l y would ind ica te that the total abundance of both e l e m e n t s is a cons tan t and if one is p r e s e n t , the o ther cannot be. A pos s ib l e explana t ion may be that in the ca rbonaceous chondr i t e s the c h r o m i u m and m a n g a n e s e condense in d i f fe ren t f r a c t i ons f rom the p r i m o r d i a l m a t t e r w h e r e a s in the o r d i n a r y chondr i t e s they condense to- ge ther . This may be p a r t i a l l y exp la ined by a change f rom chalcophi l ic to l i thophi l ic chemica l behav io r with s m a l l changes in p h y s i c a l - c h e m i c a l condi t ions .

The m a j o r d i f fe rence be tween the c a r b o n a c e o u s chondr i t e s and the o r d i n a r y chondr i t e s a p p e a r s to be in v a r i a t i o n s in the a tomic abundance of m a n g a n e s e , r a t h e r than in the c h r o m i u m content . This may ind ica te that the

Chem. Geol., 3 (1968) 313-322 319

c h r o m i u m and m a n g a n e s e a r e f r a c t i o n a t e d unequa l ly be tween the low t e m p e r a t u r e m a t r i x and high t e m p e r a t u r e s i l i c a t e phase.

The abso lu te abundances f o r c h r o m i u m fal l within the r ange (1 .0-1 .4" 104 a t o m s p e r 106 a t o m s Si) g iven f o r c a r b o n a c e o u s chondr i t e s . F o r m a n g a n e s e , the abundances a g r e e (5200-9500 a t o m s pe r 106 a toms Si) with the excep t ion of the type III c a r b o n a c e o u s chondr i t e s . The m a n g a n e s e abundances a r e about 10% lower than those d e t e r m i n e d by Moore and Brown (1962) and a r e e s s e n t i a l l y the s a m e as those s e l e c t e d by Mason (1962) f r o m wet a n a l y s e s by Wiik (1956).

ACKNOWLEDGEMENT

The au tho r s wish to thank Dr. H.B. Wiik fo r supplying the s a m p l e s of c a r b o n a c e o u s chond r i t e s and the C e n t e r fo r M e t e o r i t e S tudies at A r i z o n a State U n i v e r s i t y fo r the o the r chondr i t e s a m p l e s used in th is inves t iga t ion .

One of us (A.M.Y.) is a l so indebted to the A r i z o n a State U n i v e r s i t y Foundat ion fo r f i nanc ia l suppor t th rough a Gradua te R e s e a r c h F e l l o w s h i p and to NASA for p a r t i a l suppor t unde r g ran t NASA-Ns G 399.

%Or 0.44

0.42

0.40

0.38

0.36

0.34

0.32

o/ 07 04 /

140

0 7 06 03 ./o

0 2 0 o . ;2 ' a ~ 4 ' a~,6 ' o/o Mn Fig.3 . C h r o m i u m - m a n g a n e s e r e l a t i o n s h i p in L group chondr i t e s . 1 =

Al f i ane l lo ; 2 = B ju rbo le ; 3 = B r u d e r h e i m ; 4 = Chantonnay; 5 = Colby, Wiscons in ; 6 = D h u r m s a l a ; 7 = E rgheo ; 8 = F a r m i n g t o n ; 9 = Holbrook; 10 = K i s v a r s a n y ; 11 = Ku t t i ppu ram; 12 = Leedey ; 13 = Modoc; 14 = New Concord ; 15 = Ny i r ab rany .

320 Chem. Geol., 3 (1968) 313-322

0.43

% C r

0.42

0.4'

0 6

0.40 0 5 / /

0.39 / f12

0.38 ~ 01 0.37 3

09

' • i | i

0"3~20 0,2.1 0.22 0.23 0.24 -AMn

F i g . 4 . C h r o m i u m - m a n g a n e s e r e l a t i o n s h i p in H g r o u p c h o n d r i t e s . 1 = A l l e g a n ; 2 = A r c h i e ; 3 = B e a r d s l e y ; 4 = D o k a c h i ; 5 = H e s s l e ; 6 = K e s e n ; 7 = M e r u a ; 8 = P a n t a r ; 9 = P l a i n v i e w ; . 10 = R i c h a r d t o n ; 11 = R o s e C i t y ; 12 = S a l i n e .

TABLE V

99% confidence levels for the abundance ratios Mn/Cr in chondrites

Mn/Cr

Cc II 0.48 _+ 0.05 III 0.34 + 0.17 L 0.63 + 0.03 H O.57 + 0.02

T A B L E VI

A tomic a b u n d a n c e s r e l a t i v e to Si = 106 a t o m s

Cr Mn

Cc I (Orgueil) 14,000 8,200 II 12,000 + 120 5,400 + 75 HI 13,000 +_ 790 4,000 + 690 L ii,000 + 770 7,100 + 390 H 13,000 + 580 7,3Q0 + 300

Chem. Geol . , 3 (1968) 313-322 321

R E F E R E N C E S

A h r e n s , L.H., 1964. S i -Mg f rac t iona t ion in ehondr i t e s . Geochim. C o s m o e h i m . Acta , 28: 411--423.

A h r e n s , L.H., Edge, R.A. and Tay lo r , S.R., 1960. The un i fo rmi ty of concen t ra t ion of l i thophile e l e m e n t s in chond r i t e s - with p a r t i c u l a r r e f e r e n c e to Cs. Geochim. C o s m o e h i m . Acta, 20: 260-272.

Green land , L. and Lover ing , J .F . , 1965. Minor and t r a c e e l e me n t abundances in chondr i t ic m e t e o r i t e s . Geochim. C o s m o c h i m . Acta, 29: 821-858.

L a t i m e r , J.W. and Ande r s , E., 1967. Chemica l f r ac t i ona t ions in m e t e o r i t e s . 2. Abundance p a t t e r n s and the i r i n t e rp re t a t i on . Geoehim. C o s m o c h i m . Aeta, 31: 1239-1270.

Mason , B., 1962. Me teo r i t e s . Wiley, New York, N.Y., 274 pp. Moore , C.B. and Brown, H., 1962. The d i s t r ibu t ion of m a n g a n e s e and t i t an ium in stony

m e t e o r i t e s . Geochim. C o s m o c h i m . Acta, 26: 497)-502. Nichiporuk, W., Chodos, A., Helin, E. and Brown, It., 1967. De te rmina t ion of i ron,

nickel , cobalt , c a l c ium, c h r o m i u m and m a n g a n e s e in stony m e t e o r i t e s by X - r a y f l u o r e s c e n c e . Geochim. C o s m o c h i m . Aeta, 31: 1911-1930.

Urey , tt .C. and Cra ig , H., 1953. The compos i t ion of s tone m e t e o r i t e s and the or igin of the m e t e o r i t e s . Geochim. C o s m o c h i m . Acta, 4: 36-82.

Wiik, H.B., 1956. The c h e m i c a l compos i t ion of some stony m e t e o r i t e s . Geochim. C o s m o c h i m . Acta, 9: 279-289.

Ya tes , A.M.. 1966. X - r a y F l u o r e s c e n c e A n a l y s i s of Chondr i t ic M e t e o r i t e s . T h e s i s . Ar izona State Univ. , T e m p e . Ariz.~ 83 pp.

322 Chem. Geol. , 3 (1968) 313-322