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The Holbrook, Arizona, chondrite
Geochimica et Cosmochimiea Acta, 1961, Vol. 21, pp. 276 to 283. Pergamon Press Ltd. Printed in lh-orthernIreland
The Holbrook, Arizona, chondrite :BlXIAN ~IAsoN* and H. B. WnK'~ * The American ~Iuseum of N a t u r a l History, ~'ew York and ~" Geologiska Forskningsanstalten, Otnfis, Finland
(Received 18 February 1960) A b s t r a c t - - T h e Holbrook ehondrite has been reanalysed, ~'ith tile following results: F e 7-18, Hi 1.09, Co 0.054, Cu 0-0096, FeS 7-91, SiC2 40-11, Tie2 0-14, A1203 1.90, Cr203 0-5I, F e e 12-0I, MnO 0"37, MgO 25-18, CaO 1.74, Na20 0.93, K~O 0.10, P . O , 0-40, It~O 0.27, (3 0-06; t o t a l 99-99. The mineralogical composition is olivine (Fo~4), hypersthcno (En;e), plagioclaso (An,s), nickel-iron, troilite, chromite, and possibly apatite. The density of the meteorite is 3.56. A s u m m a r y of the data on the abundances of Ba, 13i, Cs, Cu, In, P b , Li, Hg, Rb, So, Se, Sr, Te, Tl, Th, U, V, Y a n d Zr in this meteorite is included.
INTRODUCTION Oh~ 19 July, 1912, a shower of stony meteorites fell near the section house of Aztec, on the Santo :Fe R a i l w a y some 6 miles cast of Holbrook, INavajo County, Arizona. The circumstances of the fall were described b y FOOTE (1912) and B[V.nl~mL (1912). ~FooTE states t h a t the fall occurred between 6.20 and 6.40 p.m., whereas h[Em~ILn quotes the Holbroolr Zrews as saying t h a t the fall took place a b o u t 7.15 p.m. The location of the fall, according to :FooTE, is 34057 ' N, 11002 , W, b u t :P~Io~ and HEY (1953) give it as 34054 ' xN, 110~ ' W; the latter figures are for the town of Holbrook, n o t for the actual place of fall, for which those of ~FOOTE are correct. The stones were scattered over an elliptical area rouglfly estimated b y two finders to be a b o u t 3 miles long and } mile wide. FOOTE, at t h a t time operating the l?oote h[ineral Company of Philadelphia, arranged to purchase all stoncs collected, and over a period of 2 months obtained more than 14,000 stones (twenty-nine ranged in size from 1020 to 6665 g, 6000 from 1 to 1000 g each, and the remainder were smaller). He recovered a total weight of 208 kg, and he estimated t h a t some 10 kg was kept b y the finders or otherwise distributed; the total weight of the fall was thus at least 218 kg. Specimens of the Holbrook fall have been widely distributed, and it is intriguing to note that the comprehensive catalogue of :Pl~Io~ and HEY (1953) lists the whereabouts of some 87 kg, leaving a large a m o u n t unaccounted for. Much of this material is presumably in institutional and private collections throughout the world. The mineralogical and chemical composition of the Holbrook meteorite was described both b y :FOOTE (1912) and ~[ERRILL (1912), the comprehensive chemical analysis in hIEicnmT,'s paper being the work of J. E. ~VnIT}'IELD. However, as ~VAnL (1950a) pointed out, this analysis is unreliable, showing only a trace of Na20. As the Itolbrook chondrite is excellent research material, being fresh and unaltered, is available in m a n y institutions, and has been used in a number of investigations of minor and trace elements in meteoritic material, we decided to reanalyse this meteorite. We selected a single stone (catalogue no. 586) from the collection of The
276
The Holbrook, Arizona, chondrito
American hluseum of N a t u r a l History, weighing 2316 g, for investigation. We have also made some chemical determinations on material from the Chicago Natural H i s t o r y ~[useum. GENERAL DESCRIPTION
The circumstances of tile fall, and tile surface features of tile stones, have been well described b y :FOOTE. The individual stones, even the smallest, are usually completely covered with a thin crust of black glassy material. The glassy crust on some of the stones, especially the larger ones, shows typical radial flowage lines and thereby indicates the front end of the stones as t h e y passed through the earth's atmosphere. The interior of the stones is compact, and light grey in colour, and the broken surface shows small particles of nickel-iron and larger particles of troilite; the silicates are very fine-grained, b u t occasional chondrulcs are visible to tile naked eye. The density of a weighed piece of the analysed specimen was determined b y evacuating (by means of an oil pump) the piece under a bell jar, and then running in carbon tetrachloride and measuring the apparent loss of weight. :By this technique it was hoped to avoid error caused b y retention of air in the slightly porous meteorite. The density thereby determined was 3.56. This is probably more nearly correct than the figure 3.48 given b y ~[E~nILL. The potassium-argon age of the Holbrook meteorite was determined b y GEISS and HEss (1958) and found to be 4-4 :]: 0.1 • 109 years. I-~[INERALOGICAL CosIrOSITIO~"
The minerals identified in the stone are olivine, hypersthene, plagioclase, troilite, nickel-iron, and chromite; apatite (or merrillite) is p r o b a b l y present in small a m o u n t b u t was not identified. ~Ierrill records occasional monoclinic pyroxene; however, we have carefully examined a pyroxene concentrate from this meteorite and have found only orthorhombie pyroxene. To.~mI~-so~-, who described the mineralogical composition in :FOOTE (1912), claims the presence of magnetite as small black grains in the mass of the meteorite; we believe, however, t h a t this mineral was actually chromite (although there is p r o b a b l y a little magnetite in the glassy crust). To.~mI~-so~- also described the occurrence of a patch of redbrown spinels set in quartz; BInR~ILL saw nothing of this sort, and nor have we. :From To~mI~-soMs description the quartz m a y have been p!agioclase and the redbrown spinels chromite, which would accord with the overall composition of the stone; the occurrence of free quartz in a stone with so much olivine is improbable. Optical data on the individual minerals are as follows. Olivlne. The indices of refraction are: a = 1.683, ~ --~ 1-722; these indices indicate a composition of :Fo~a, according to the data of POLDERV,~RT (1950); this composition was confirmed b y the X-ray method of YoDER and S~A~IA (1957). Hypersthene. The indices of refraction are: cr ~ 1-677, ~, = 1.691; these indices indicate a composition of En~s , according to the determinative curve of K u x o (1954). Plagioclase. The indices ofrefractionare: ~ = 1.535, 7~ = 1-543; these indices indicate a composition of Ant5. :By treating a sample of the crushed meteorite with 1:1 HC1 olivine, nickel-iron, 277
BaI.~.x 5IAsox and It. B. ~rIIIi:
troilite, and probably apatito were dissolved, leaving a residue of hypersthene, plagioclase and chromite. The silica produced by the decomposition of the olivine was removed by dissolving in Na2CO a solution. In this way pure grains of hypersthene and plagioclase were isolated for determinations of refractive index. The nickel-iron in the Holbrook meteorite has been carefully stuiiied by U•Ey and hL~u (1959), who recognized kamacite, taenite and plessite. An X-ray powder photograph of the nickel-iron showed strong lines of taenito and weak lines of kamaeite. The troilite was separated and analysed by ~VIIITFIELD (~[ERRILL, 1912), who obtained l~e 63.62, S 36.50, Ni, Co, Cu, none; a result close to the theoretical composition of FeS. Diamonds have been searched for in the ttolbrook meteorite (Uric.x"et al., 1957); they found none, and give <0.02 per cent as an upper limit for the possible diamond content. A thin section of the meteorite shows chondrules, 0.5-1-5 mm in diameter, of granular olivine and finely prismatic, sometimes radiating hypersthene, set in a fine-grained (0.1 mm diameter and smaller) ground-mass of olivine and hypersthene. Irregular opaque grains of nickel-iron, troilite and chromite are present, varying in size from 1 mm across down to dust-like material dispersed through the ground mass. A very small amount of brown limonitie staining is associated with some of the opaque grains. No plagioclase was identified in thin section, although it was found in the residue left after dissolving a portion of the meteorite in 1:1 HCI; it is present in small amount evidently as very small interstitial grains. I t should be noted that both the hypersthene and olivine give sharp peaks in the X-ray diffraetometer, implying that the composition of both these minerals is quite uniform. This is supported by the optical data. The association of an olivine with hypersthene with a somewhat higher BIg/Fe -b Mg ratio is consistent with equilibrium crystallization in the system ~IgO--~eO--Si02 (:Boww~ an4 SotrAmER, 1935). The mineralogy of the ttolbrook ehondrite suggests that these minerals originally crystallized under equilibrium conditions, and that the meteorite is not a chance aggregate of minerals of random and variable composition. CIIEMICAL COBIPOSITIOh" The chemical analysis is given in Table 1, in the conventional form expressed as oxides, troilite, and metal; in terms of the individual elements; and recalculated on a volatile-free basis. Some elements were determined by emission spectrography, as well as by conventional wet chemical methods. The spectrographic determinations were made in the spectrographic laboratory of the Geology Department of the University of Chicago on a sample of the ttolbrook meteorite obtained from the Chicago INatural History ~Iuseum. A comparison of the two sets of results are given in Table 2. The agreement is close except for aluminium. The figures given in Table 1 are the results of wet chemical analysis on the sample from the American l~Iuseum of ~Natural History. Sodium and potassium have been determined several times in ttolbrook. The results, and the methods used, are set out in Table 3. 278
The Holbrook, Arizona, ehondrito Table I. Chemical analysis of the ttolbrook meteorite (A)
(B)
Fo Ni Co Cu FeS SiO 2 TiO 2 Al20 s CrsO a FeO Mn0 MgO CaO
7-18 1.09 0.052 0.0096 7.94 40-11 0.14 1-90 0.45 12.01 0-37 25.18 1.74
I-I C O ~'a 3Ig AI Si P S K Ca Ti Cr
0.029 0.06 36.471 0.69 15.18 1.00 18-74 0-17 2.90 0-08 1-24 0.08 0.31
~'a20 K20 I)205 I=IoO+ O
0-93 0-I0 0.40 0.27 0.06 99.99
5In Fo Co Ni Cu
0.29 21-56 0.052 1.09 0.0096 99.99
(C) Na 1.14 5Ig 25.07 Al 1.65 Si 30.95 P 0.28 K 0.13 Ca 2.05 Ti 0-13 Cr 0.58 .~In 0.48 Fe 35.61 Co 0.087 :Ni 1.80 99.95
(A) Chemical analysts expressed as nickel-iron, troilito and oxides (all ]-I as H20, all C as C (both free and comblncd)). (B) Chemical analysis expressed as elements, with calculated figure for oxygen. (C) Chemical analysis recalculated ell a volatile-free (O, C, S, H) basis. Table 2. Comparison of results of (A) spectrographio analysis of a sample of Holbrook from the Chicago Natural H i s to r y 3[useum and (B) we~ chemical analysis of a sample of I-Iolbrook from the American Museum of Natural History
(A) Co Ni Ti A1 5In Cr V Cu Sc Y
(B)
(%).
(%)
0.054 1.01 0.06 1.27 0.28 0-35 (p.p.m.) 98 96 7.4 2-3
0.052 1.09 0.08 1.00 0.29 0.31
The normative mineral composition, expressed as weight percentages, is given in Table 4. This has been calculated as suggested by WAttL (1950b), except that we prefer to calculate 1)205 as apatite, not merrillite; the composition of merrillito is 279
BRtX-'r MASO-',-and It. B. XVIIK T a b l e 3. S o d i u m a n d p o t a s s i u m d e t e r m i n a t i o n s on t h e H o l b r o o k meteorite
Na
K
Method used
0"58
0-13
0-~9
0'08
0-73
0.08 0.087
Lawrence Smith, K precipitated as KoPtC16 ($~,Lxn-L,1950b) Lawrence Smith, K precipitated as IC13(C6Hs)a (this paper) Emission spectrography (AzaaE~'s etal., 1952) Itigh-temperaturo distillation, followed by flame photometry (EDWARDSand UnEY, 1955)
n o t well established, being based on a single analysis of a small amount of impure material, and this mineral m a y well be a variety of apatite. I t should be emphasized t h a t the normative mineral composition calculated from the chemical analysis can only approximate the actual mineralogy of the meteorite. The calculation involves several arbitrary procedures. Alumina is calculated entirely as feldspar, although it is known t h a t small amounts are present in pyroxene (an analysis, hLtsox and Wm~, 1960, of orthorhombic pyroxene from the 5Iiller, Arkansas, chondrite shows 1-22 per cent A1203). The Ti02 is calculated as ilmenite, b u t the titanium is present wholly or in largo p a r t in the ferromagncsian minerals, pyroxene and olivine. The calculation assumes t h a t the :Fe/Mg ratio is the same in all the fcrromagnesian minerals, b u t measurements of the optical properties of these minerals show t h a t this is not the case. Nevertheless, when interpreted with care and discrimination, the normative mineral composition provides a useful guide to the actual mineral composition, and conversely the actual mineral composition can be most readily correlated with the chemical composition through the calculated norm. Table 4. ~'ormative mineral composition of the Itolbrook meteorite
% Nickel-iron Troilite Olivine lIypersthcne Diopside Orthoclase Albite Anorthite Apatite Chromite Ilmenite
8.33 7.94 37.63 30.16 4.27 0.62 7.86 0-70 0-94 0.76 0-25
The normative mineral composition of the tIolbrook meteorite correlates well with the observed mineral composition. As mentioned previously, apatite was n o t observed b u t is presumably present. The small a m o u n t of titanium is probably not" present as ilmenite, b u t in the silicate phases (the analysis of pyroxene from tlm 280
The Holbrook, Arizona, chondrite
Ziiller, Arkansas, ehondrite shows 0-21 per cent TiO,). The potassium is almost certainly in solid solution in the plagioclase phase. The calculated diopside is in the hyperstheno phase. Assuming the compositions for the olivine and pyroxcne deduced from optical and X-ray measurements, the percentage of ]~IgO would be 24.6 (against 25.18 actually determined) and :FeO would be 13.0 (against 12.01 actually determined, to which the 0.37 per cent hInO should be added). The agreement between these figures is satisfactory. The chemical analysis shows that the ttolbrook stone, according to the classification of 1)RIO~ (1920) falls into his group of hypersthene-olivine chondrites. According to the classification of UREY and CRAIG (1953), it belongs to their L group, since it contains low total iron (21.56 per cent, the average t~or the L group being 22.33 per cent), ttolbrook is closely comparable chemically and mincralogically with a number of hypcrsthene-olivine chondrites, including h[onte das :Fortes, Linum, Varpaisj~irvi, and ~IeKinney (]VnK, 1956), Launton (I)~tlOn, 1916), Crumlin (:FLETCHER, 1921), and Guidder (JERE~tIZ~'~ and SA~'DREA, 1953). ~IIh*OR AzN'DTRACE ELE.~IEh'TS
Probably on account of its wide distribution and thus its availability, t{olbrook has been used for many determinations of minor and trace elements in meteoritic material. We have attempted to collcc~ as many of these determinations as possible and they are presented below. Barium: 9 p.p.m. (PIh-so~ et al. 1953; by emission spectrography); 3.6 p.p.m. (REED et al., 1960; by neutron activation). Bismuth: 0.0021 p.p.m. (EIIsIANh"and :[-IuIzEh*GA,1959; by neutron activation); 0.002-0.0075 p.p.m. CREED et al., 1960; by neutron activation). Caesium: 0-49 p.p.m. (GORDOn" et al., 1957; by isotope dilution); 0.283 p.p.m. {WEBSTER et al., 1958; by isotope dilution); 0.146 p.p.m. (GAST, 1960; by isotope dilution). Chromium: 3500 p . p . m . (this paper; by emission spectrography); 3100 p.p.m. (this paper; by wet chemical analysis); 2150 p.p.m. (BATE el al., 1960; by neutron activation). Copper: 96 p.p.m. (this paper; by emission speetrography). Europium: 0.081 p.p.m. (:BATE et al., 1960; by neutron activation). Indium: 0.001 p.p.m. (SctIIh'DEWOLF and WA~LGRE~', 1960; by neutron activation). Lead: 0.3-0.5 p.p.m. (BL~sm~LL and HEss, 1958; byisotope dilution); 0.3-0.6 p.p.m. (REED et al., 1960; by neutron activation). Lithium: 3.3 p . p . m . (PI~-so~- et al., 1953; by emission spectrography). ~ercury: 0.052 p.p.m.-Hg 2~ (EH~IA~%" and ttUIZE~'(~A, 1959; by neutron activation). Rhodium: 0-15 p.p.m. (Sctm','DZWOL~ and WAnLGnE~', 1960; by neutron activation). Rubidium: 8 p . p . m . (PI~'so~ et al., 1953; by emission speetrography); 2-3 p.p.m. (W~.BSTE~ et al., 1958; by isotope dilution); 2-22 p . p . m . (GAsT, 1960; by isotope dilution). Scandium: 8.5 p.p.m. (PIh-so~- et al., 1953; by emission spectrography); 7.4 281
J3R~_-r 5I~sox and H. B. ~V~xK p . p . m . (this p a p e r ; b y e m i s s i o n s p e c t r o g r a p h y ) ; 9.7 p . p . m . (:BATE et al., 1960; b y neutron activation). S e l e n i u m : 13.3 p . p . m . (SoHIXDEWOLF, 1960; b y n e u t r o n a c t i v a t i o n . Silver: 0.04 p . p . m . (ScHIXD~WOLr a n d W,~HLGREX, 1960; b y n e u t r o n a c t i vation). S t r o n t i u m : 13 p . p . m . (Prxso~- et al., 1953; b y e m i s s i o n s p e e t r o g r a p h y ) ; 12 p . p . m . (G,tsT, u n p u b l i s h e d ) . T e l l u r i u m ; 0.62 p . p . m . (Scm~'DEWOLF, 1960; b y n e u t r o n a c t i v a t i o n ) . T h a l l i u m : 0.0004-0.0038 (REED el al., 1960; b y n e u t r o n a c t i v a t i o n ) . T h o r i u m : 0.038 p . p . m . (BATE et al., 1959; b y n e u t r o n a c t i v a t i o n ) . U r a n i u m : 0.014 p . p . m . (HA.~rAOUCHI et al., 1957; b y n e u t r o n a c t i v a t i o n ) . V a n a d i u m : 98 p . p . m . (this p a p e r ; b y e m i s s i o n s p e c t r o g r a p h y ) . Y t t r i u m : 2.3 p . p . m . (this p a p e r ; b y e m i s s i o n s p e c t r o g r a p h y ) . Z i r c o n i u m : 28 p . p . m . (P~-so~- et al., 1953; b y e m i s s i o n s p e e t r o g r a p h y ) . N o t e a d d e d i n p r o o f : - - D e t e r m i n a t i o n o f t h e n o b l e m e t a l s b y c u p e l l a t i o n followed b y emission s p e c t r o g r a p h y ( a n a l y s t s : A. LSFanr.N, P. V s a n d H . B. W I I K ) g a v e t h e following r e s u l t s (all in p . p . m . ) : R u 0.060; l~h 0.064; P d 0.44; 0 s 0.16; I r 0-24i Pb 0.44; A u 0.04. Acknowledgements~Ve are indebted to the J. Lawrence Smith Fund of the National Academy of Sciences for a grant towards the cost of this investigation. ~Vo would also express our gratitude to Professor W. tt. l~E~u[ous~ and Mr. OrcA Jo~.Nstru for the use of the facilities of the spectrographic laboratory of the Geology Department oftho University of Chicago, to Dr. :H. S. YODER for assistance in the determination of the composition of the olivine b y X-ray technique, and to ~Ir. E. P. :HENDERSONfor critical reading of the manuscript.
~EFERE~CES AImENs L. H., PLXSON~V. H. and I ~ m N S ~I. ~I. (1952) Association of rubidium and potassium and their abundance in common igneous rocks and meteorites. Geochim.etGosmochim. Acta2, 229-242. BATE G. L., :HUIZENOAg. 1%. and I:~OTRATZ:It. A. (1959) Thorium in stone meteorites by neutron act;ivation analysis. Geochim. et Cosmochim. Acta 16, 88-100. BATE G. L., POTRATZ:H. A. and HulzE~xox ft. R. (1960) Scandium, chromium and europium in stone meteorites by simultaneous neutron activation analysis. GeocMm. et CosmocMm. Acta 18, 101-107. BOWEN lq. L. and Scm~.mv.n J. F. (1935) The system !~Ig0--Fc0--SiO e. Amer. J. Sci. 29, 151-217. :ED~VARDSG. and Unv.Y H. C. (1955) Determination of alkall metals in meteorites by a distillation process. OeocMm. et Cosmochim. Acta 7, 154-168. E r ~ I ~ W. D. and HULZENOAJ. R. (1959) Bismuth, thallimn and mercury in stone meteorites by activation analysis. GeocMm. et Cosmochim. Acta 17, 125-135. FL~.TCILERL. (1921) The meteoritic stone seen to fall near Crumlin, County AntrLm, on September 13, 1902. l]liner, l]lag. 19, 149-162. FooTv. W. ~I. (1912) Preliminary note on the shower of meteoric stones near Holbrook, Navajo County, Arizona, July 19, 1912, including a reference to the Pcrseid swarm of meteors visible from July 11 to August 22. A m e r J . Sci. 34, 437-456. GAST P. W. (1960) Alkali metals in stone meteorites. Geochlm. et CosrnocMrn. Acta. 19, 1--4. GEISS J. and HEss D. C. (1958) Argon-potassium ages and the isotopic composition of argon from meteorites. Astrophys. J. 127, 224-235. GORDONB. ~]'., FRIEDSIA-~L. and EDWARDS G. (1957) Caesium in stony meteorites. GeocMm. et GosmocMm. Acta 12, 170-171. 282
The Holbrook, Arizona, chondrit~) HAXtAaUCtIIH., REED G. ~V. and TU~KEvIClt A. (1957) U r a n i u m and barium in stone meteorites. Gcochim. et Cosmochim. Acta 12, 337-347. JEnE.~hm E. and S_~'~'I)nEAA. (1953) Sur la meteorite do Guidder. Geochlm. et Cosniochim. Acts 4, 83-88. K ~ o H. (1954) Study of orthopyroxenes from volcanic rocks. Amer. llIin. 39, 30-46. 3I~s~ R. R. and HESS D. C. (1958) Lead from some stone meteorites. J. Chem. -Phys. 28, 1258-1259. ~IAso.~ ]3. a n d ~VHK H. B. (1960) The ~liller, Arkansas, chondrite. Geochim. et Cosmochim. Acta. 21, 266-271. ~IER~mL G. P. (1912) A recent meteorite fall near Holbrook, Navajo County, Arizona. Smithsonian _~lisc. Coll. 60, No. 9. Pl,~so,'~ W. H., An~E~-S L. It. a n d FRA.','CKZI. L. (1953) The abundances of Li, Si, Sr, Ba, and Zr in chondrites a n d some ultramafie rocks. Gcochim. et Cosmochim. Acta 4, 251-260. POLDE~VA~LRT A. (1950) Correlation of physical properties and chemical composition in the plagioclase, olivine, and orthopyroxene series. Amer. ~lin. 35, 1067-1079. P1~Io~ G. T. (1916) The meteoric stoncs of LaImton, ~Varbreccan, Cronstad, Daniel's Kuil, Khairpur, and Soko-]3anja. ~llincr. 2llag. 18, 1-25. Palor~ G. T. (1920) The classification of meteorites. ~lIiner. ~llag. 19, 51-63. PItieR G. T. a n d ItEx" M. H. (1953) Catalogue of 2Ieteoritcs, with Special 1reference to those Rep. resentezl in the Collection of the British ~lluseum (Natural History). British ZIuseum, London. :REED G. W., K I a o s m K. and TU~KEVIOHA. (1960) Concentrations of some heavy elements in meteorites b y activation analysis. Geochim. et Cosmochira. Acta. 20j 122-140. SCm~;D~WOI~, V. (1960) Selenium and tellurium content of stony meteorites b y neutron activation. Geochim. et Cosmochim. Acta 19, 134-138 SOm~,~DEWOL~" U. and XVa_~L~RE.~ ~I. (1960) The rhodium, silver and indium content of some chondritic meteorites. Geochim. et Cosmochim. Acta 18, 36-41. T ~ . y It. C. and CnAIa H. (1953) The composition of the stone meteorites and the origin of the meteorites. Geochim. et Cosmochim. Acta 4, 36-82. IJREr H. C., 5IELE A. and ~IAYEDA T. (1957} Diamonds in stone meteorites. Geochirn. et Cosmochim. Acta 13, 1--4. UttEr It. C. and ZIAY~DAT. (1959) The metallic particles of some chondrites. Geochbn. et COSmochim. Acta 17, 113-124. ~VAnT~W. A. (1950a) A check on some previously reported analyses of stony meteorites with exceptional high content of salic constituents. Geochim. e~ Cosmochim. Acta 1, 28-32. ~VAHLW. (1950b) The statement of chemical analyses of stony meteorites and the interpretation of the analyses in terms of m i n e r a l s . . ~ l i n e r . ~llag. 29, 416-426. ~VEBSTER I~. K., ~IORGAI~T~. W. a n d S:~AL~S A. A. (1958) Caesium in chondrites. Geochim. e~ Cosmochim. Acta 15, 150-152. ~Vns: tI. ]3. (1956) The chemical composition of some stony meteorites. Gcochim. et Cosmochim. Acta 9, 279-289. YODER H. S. and SAHA.~t~ T. G. (1957) Olivine X-ray determinative curve. Amer. Min. 42, 472--491.
283
The Holbrook, Arizona, chondrite :BlXIAN ~IAsoN* and H. B. WnK'~ * The American ~Iuseum of N a t u r a l History, ~'ew York and ~" Geologiska Forskningsanstalten, Otnfis, Finland
(Received 18 February 1960) A b s t r a c t - - T h e Holbrook ehondrite has been reanalysed, ~'ith tile following results: F e 7-18, Hi 1.09, Co 0.054, Cu 0-0096, FeS 7-91, SiC2 40-11, Tie2 0-14, A1203 1.90, Cr203 0-5I, F e e 12-0I, MnO 0"37, MgO 25-18, CaO 1.74, Na20 0.93, K~O 0.10, P . O , 0-40, It~O 0.27, (3 0-06; t o t a l 99-99. The mineralogical composition is olivine (Fo~4), hypersthcno (En;e), plagioclaso (An,s), nickel-iron, troilite, chromite, and possibly apatite. The density of the meteorite is 3.56. A s u m m a r y of the data on the abundances of Ba, 13i, Cs, Cu, In, P b , Li, Hg, Rb, So, Se, Sr, Te, Tl, Th, U, V, Y a n d Zr in this meteorite is included.
INTRODUCTION Oh~ 19 July, 1912, a shower of stony meteorites fell near the section house of Aztec, on the Santo :Fe R a i l w a y some 6 miles cast of Holbrook, INavajo County, Arizona. The circumstances of the fall were described b y FOOTE (1912) and B[V.nl~mL (1912). ~FooTE states t h a t the fall occurred between 6.20 and 6.40 p.m., whereas h[Em~ILn quotes the Holbroolr Zrews as saying t h a t the fall took place a b o u t 7.15 p.m. The location of the fall, according to :FooTE, is 34057 ' N, 11002 , W, b u t :P~Io~ and HEY (1953) give it as 34054 ' xN, 110~ ' W; the latter figures are for the town of Holbrook, n o t for the actual place of fall, for which those of ~FOOTE are correct. The stones were scattered over an elliptical area rouglfly estimated b y two finders to be a b o u t 3 miles long and } mile wide. FOOTE, at t h a t time operating the l?oote h[ineral Company of Philadelphia, arranged to purchase all stoncs collected, and over a period of 2 months obtained more than 14,000 stones (twenty-nine ranged in size from 1020 to 6665 g, 6000 from 1 to 1000 g each, and the remainder were smaller). He recovered a total weight of 208 kg, and he estimated t h a t some 10 kg was kept b y the finders or otherwise distributed; the total weight of the fall was thus at least 218 kg. Specimens of the Holbrook fall have been widely distributed, and it is intriguing to note that the comprehensive catalogue of :Pl~Io~ and HEY (1953) lists the whereabouts of some 87 kg, leaving a large a m o u n t unaccounted for. Much of this material is presumably in institutional and private collections throughout the world. The mineralogical and chemical composition of the Holbrook meteorite was described both b y :FOOTE (1912) and ~[ERRILL (1912), the comprehensive chemical analysis in hIEicnmT,'s paper being the work of J. E. ~VnIT}'IELD. However, as ~VAnL (1950a) pointed out, this analysis is unreliable, showing only a trace of Na20. As the Itolbrook chondrite is excellent research material, being fresh and unaltered, is available in m a n y institutions, and has been used in a number of investigations of minor and trace elements in meteoritic material, we decided to reanalyse this meteorite. We selected a single stone (catalogue no. 586) from the collection of The
276
The Holbrook, Arizona, chondrito
American hluseum of N a t u r a l History, weighing 2316 g, for investigation. We have also made some chemical determinations on material from the Chicago Natural H i s t o r y ~[useum. GENERAL DESCRIPTION
The circumstances of tile fall, and tile surface features of tile stones, have been well described b y :FOOTE. The individual stones, even the smallest, are usually completely covered with a thin crust of black glassy material. The glassy crust on some of the stones, especially the larger ones, shows typical radial flowage lines and thereby indicates the front end of the stones as t h e y passed through the earth's atmosphere. The interior of the stones is compact, and light grey in colour, and the broken surface shows small particles of nickel-iron and larger particles of troilite; the silicates are very fine-grained, b u t occasional chondrulcs are visible to tile naked eye. The density of a weighed piece of the analysed specimen was determined b y evacuating (by means of an oil pump) the piece under a bell jar, and then running in carbon tetrachloride and measuring the apparent loss of weight. :By this technique it was hoped to avoid error caused b y retention of air in the slightly porous meteorite. The density thereby determined was 3.56. This is probably more nearly correct than the figure 3.48 given b y ~[E~nILL. The potassium-argon age of the Holbrook meteorite was determined b y GEISS and HEss (1958) and found to be 4-4 :]: 0.1 • 109 years. I-~[INERALOGICAL CosIrOSITIO~"
The minerals identified in the stone are olivine, hypersthene, plagioclase, troilite, nickel-iron, and chromite; apatite (or merrillite) is p r o b a b l y present in small a m o u n t b u t was not identified. ~Ierrill records occasional monoclinic pyroxene; however, we have carefully examined a pyroxene concentrate from this meteorite and have found only orthorhombie pyroxene. To.~mI~-so~-, who described the mineralogical composition in :FOOTE (1912), claims the presence of magnetite as small black grains in the mass of the meteorite; we believe, however, t h a t this mineral was actually chromite (although there is p r o b a b l y a little magnetite in the glassy crust). To.~mI~-so~- also described the occurrence of a patch of redbrown spinels set in quartz; BInR~ILL saw nothing of this sort, and nor have we. :From To~mI~-soMs description the quartz m a y have been p!agioclase and the redbrown spinels chromite, which would accord with the overall composition of the stone; the occurrence of free quartz in a stone with so much olivine is improbable. Optical data on the individual minerals are as follows. Olivlne. The indices of refraction are: a = 1.683, ~ --~ 1-722; these indices indicate a composition of :Fo~a, according to the data of POLDERV,~RT (1950); this composition was confirmed b y the X-ray method of YoDER and S~A~IA (1957). Hypersthene. The indices of refraction are: cr ~ 1-677, ~, = 1.691; these indices indicate a composition of En~s , according to the determinative curve of K u x o (1954). Plagioclase. The indices ofrefractionare: ~ = 1.535, 7~ = 1-543; these indices indicate a composition of Ant5. :By treating a sample of the crushed meteorite with 1:1 HC1 olivine, nickel-iron, 277
BaI.~.x 5IAsox and It. B. ~rIIIi:
troilite, and probably apatito were dissolved, leaving a residue of hypersthene, plagioclase and chromite. The silica produced by the decomposition of the olivine was removed by dissolving in Na2CO a solution. In this way pure grains of hypersthene and plagioclase were isolated for determinations of refractive index. The nickel-iron in the Holbrook meteorite has been carefully stuiiied by U•Ey and hL~u (1959), who recognized kamacite, taenite and plessite. An X-ray powder photograph of the nickel-iron showed strong lines of taenito and weak lines of kamaeite. The troilite was separated and analysed by ~VIIITFIELD (~[ERRILL, 1912), who obtained l~e 63.62, S 36.50, Ni, Co, Cu, none; a result close to the theoretical composition of FeS. Diamonds have been searched for in the ttolbrook meteorite (Uric.x"et al., 1957); they found none, and give <0.02 per cent as an upper limit for the possible diamond content. A thin section of the meteorite shows chondrules, 0.5-1-5 mm in diameter, of granular olivine and finely prismatic, sometimes radiating hypersthene, set in a fine-grained (0.1 mm diameter and smaller) ground-mass of olivine and hypersthene. Irregular opaque grains of nickel-iron, troilite and chromite are present, varying in size from 1 mm across down to dust-like material dispersed through the ground mass. A very small amount of brown limonitie staining is associated with some of the opaque grains. No plagioclase was identified in thin section, although it was found in the residue left after dissolving a portion of the meteorite in 1:1 HCI; it is present in small amount evidently as very small interstitial grains. I t should be noted that both the hypersthene and olivine give sharp peaks in the X-ray diffraetometer, implying that the composition of both these minerals is quite uniform. This is supported by the optical data. The association of an olivine with hypersthene with a somewhat higher BIg/Fe -b Mg ratio is consistent with equilibrium crystallization in the system ~IgO--~eO--Si02 (:Boww~ an4 SotrAmER, 1935). The mineralogy of the ttolbrook ehondrite suggests that these minerals originally crystallized under equilibrium conditions, and that the meteorite is not a chance aggregate of minerals of random and variable composition. CIIEMICAL COBIPOSITIOh" The chemical analysis is given in Table 1, in the conventional form expressed as oxides, troilite, and metal; in terms of the individual elements; and recalculated on a volatile-free basis. Some elements were determined by emission spectrography, as well as by conventional wet chemical methods. The spectrographic determinations were made in the spectrographic laboratory of the Geology Department of the University of Chicago on a sample of the ttolbrook meteorite obtained from the Chicago INatural History ~Iuseum. A comparison of the two sets of results are given in Table 2. The agreement is close except for aluminium. The figures given in Table 1 are the results of wet chemical analysis on the sample from the American l~Iuseum of ~Natural History. Sodium and potassium have been determined several times in ttolbrook. The results, and the methods used, are set out in Table 3. 278
The Holbrook, Arizona, ehondrito Table I. Chemical analysis of the ttolbrook meteorite (A)
(B)
Fo Ni Co Cu FeS SiO 2 TiO 2 Al20 s CrsO a FeO Mn0 MgO CaO
7-18 1.09 0.052 0.0096 7.94 40-11 0.14 1-90 0.45 12.01 0-37 25.18 1.74
I-I C O ~'a 3Ig AI Si P S K Ca Ti Cr
0.029 0.06 36.471 0.69 15.18 1.00 18-74 0-17 2.90 0-08 1-24 0.08 0.31
~'a20 K20 I)205 I=IoO+ O
0-93 0-I0 0.40 0.27 0.06 99.99
5In Fo Co Ni Cu
0.29 21-56 0.052 1.09 0.0096 99.99
(C) Na 1.14 5Ig 25.07 Al 1.65 Si 30.95 P 0.28 K 0.13 Ca 2.05 Ti 0-13 Cr 0.58 .~In 0.48 Fe 35.61 Co 0.087 :Ni 1.80 99.95
(A) Chemical analysts expressed as nickel-iron, troilito and oxides (all ]-I as H20, all C as C (both free and comblncd)). (B) Chemical analysis expressed as elements, with calculated figure for oxygen. (C) Chemical analysis recalculated ell a volatile-free (O, C, S, H) basis. Table 2. Comparison of results of (A) spectrographio analysis of a sample of Holbrook from the Chicago Natural H i s to r y 3[useum and (B) we~ chemical analysis of a sample of I-Iolbrook from the American Museum of Natural History
(A) Co Ni Ti A1 5In Cr V Cu Sc Y
(B)
(%).
(%)
0.054 1.01 0.06 1.27 0.28 0-35 (p.p.m.) 98 96 7.4 2-3
0.052 1.09 0.08 1.00 0.29 0.31
The normative mineral composition, expressed as weight percentages, is given in Table 4. This has been calculated as suggested by WAttL (1950b), except that we prefer to calculate 1)205 as apatite, not merrillite; the composition of merrillito is 279
BRtX-'r MASO-',-and It. B. XVIIK T a b l e 3. S o d i u m a n d p o t a s s i u m d e t e r m i n a t i o n s on t h e H o l b r o o k meteorite
Na
K
Method used
0"58
0-13
0-~9
0'08
0-73
0.08 0.087
Lawrence Smith, K precipitated as KoPtC16 ($~,Lxn-L,1950b) Lawrence Smith, K precipitated as IC13(C6Hs)a (this paper) Emission spectrography (AzaaE~'s etal., 1952) Itigh-temperaturo distillation, followed by flame photometry (EDWARDSand UnEY, 1955)
n o t well established, being based on a single analysis of a small amount of impure material, and this mineral m a y well be a variety of apatite. I t should be emphasized t h a t the normative mineral composition calculated from the chemical analysis can only approximate the actual mineralogy of the meteorite. The calculation involves several arbitrary procedures. Alumina is calculated entirely as feldspar, although it is known t h a t small amounts are present in pyroxene (an analysis, hLtsox and Wm~, 1960, of orthorhombic pyroxene from the 5Iiller, Arkansas, chondrite shows 1-22 per cent A1203). The Ti02 is calculated as ilmenite, b u t the titanium is present wholly or in largo p a r t in the ferromagncsian minerals, pyroxene and olivine. The calculation assumes t h a t the :Fe/Mg ratio is the same in all the fcrromagnesian minerals, b u t measurements of the optical properties of these minerals show t h a t this is not the case. Nevertheless, when interpreted with care and discrimination, the normative mineral composition provides a useful guide to the actual mineral composition, and conversely the actual mineral composition can be most readily correlated with the chemical composition through the calculated norm. Table 4. ~'ormative mineral composition of the Itolbrook meteorite
% Nickel-iron Troilite Olivine lIypersthcne Diopside Orthoclase Albite Anorthite Apatite Chromite Ilmenite
8.33 7.94 37.63 30.16 4.27 0.62 7.86 0-70 0-94 0.76 0-25
The normative mineral composition of the tIolbrook meteorite correlates well with the observed mineral composition. As mentioned previously, apatite was n o t observed b u t is presumably present. The small a m o u n t of titanium is probably not" present as ilmenite, b u t in the silicate phases (the analysis of pyroxene from tlm 280
The Holbrook, Arizona, chondrite
Ziiller, Arkansas, ehondrite shows 0-21 per cent TiO,). The potassium is almost certainly in solid solution in the plagioclase phase. The calculated diopside is in the hyperstheno phase. Assuming the compositions for the olivine and pyroxcne deduced from optical and X-ray measurements, the percentage of ]~IgO would be 24.6 (against 25.18 actually determined) and :FeO would be 13.0 (against 12.01 actually determined, to which the 0.37 per cent hInO should be added). The agreement between these figures is satisfactory. The chemical analysis shows that the ttolbrook stone, according to the classification of 1)RIO~ (1920) falls into his group of hypersthene-olivine chondrites. According to the classification of UREY and CRAIG (1953), it belongs to their L group, since it contains low total iron (21.56 per cent, the average t~or the L group being 22.33 per cent), ttolbrook is closely comparable chemically and mincralogically with a number of hypcrsthene-olivine chondrites, including h[onte das :Fortes, Linum, Varpaisj~irvi, and ~IeKinney (]VnK, 1956), Launton (I)~tlOn, 1916), Crumlin (:FLETCHER, 1921), and Guidder (JERE~tIZ~'~ and SA~'DREA, 1953). ~IIh*OR AzN'DTRACE ELE.~IEh'TS
Probably on account of its wide distribution and thus its availability, t{olbrook has been used for many determinations of minor and trace elements in meteoritic material. We have attempted to collcc~ as many of these determinations as possible and they are presented below. Barium: 9 p.p.m. (PIh-so~ et al. 1953; by emission spectrography); 3.6 p.p.m. (REED et al., 1960; by neutron activation). Bismuth: 0.0021 p.p.m. (EIIsIANh"and :[-IuIzEh*GA,1959; by neutron activation); 0.002-0.0075 p.p.m. CREED et al., 1960; by neutron activation). Caesium: 0-49 p.p.m. (GORDOn" et al., 1957; by isotope dilution); 0.283 p.p.m. {WEBSTER et al., 1958; by isotope dilution); 0.146 p.p.m. (GAST, 1960; by isotope dilution). Chromium: 3500 p . p . m . (this paper; by emission spectrography); 3100 p.p.m. (this paper; by wet chemical analysis); 2150 p.p.m. (BATE el al., 1960; by neutron activation). Copper: 96 p.p.m. (this paper; by emission speetrography). Europium: 0.081 p.p.m. (:BATE et al., 1960; by neutron activation). Indium: 0.001 p.p.m. (SctIIh'DEWOLF and WA~LGRE~', 1960; by neutron activation). Lead: 0.3-0.5 p.p.m. (BL~sm~LL and HEss, 1958; byisotope dilution); 0.3-0.6 p.p.m. (REED et al., 1960; by neutron activation). Lithium: 3.3 p . p . m . (PI~-so~- et al., 1953; by emission spectrography). ~ercury: 0.052 p.p.m.-Hg 2~ (EH~IA~%" and ttUIZE~'(~A, 1959; by neutron activation). Rhodium: 0-15 p.p.m. (Sctm','DZWOL~ and WAnLGnE~', 1960; by neutron activation). Rubidium: 8 p . p . m . (PI~'so~ et al., 1953; by emission speetrography); 2-3 p.p.m. (W~.BSTE~ et al., 1958; by isotope dilution); 2-22 p . p . m . (GAsT, 1960; by isotope dilution). Scandium: 8.5 p.p.m. (PIh-so~- et al., 1953; by emission spectrography); 7.4 281
J3R~_-r 5I~sox and H. B. ~V~xK p . p . m . (this p a p e r ; b y e m i s s i o n s p e c t r o g r a p h y ) ; 9.7 p . p . m . (:BATE et al., 1960; b y neutron activation). S e l e n i u m : 13.3 p . p . m . (SoHIXDEWOLF, 1960; b y n e u t r o n a c t i v a t i o n . Silver: 0.04 p . p . m . (ScHIXD~WOLr a n d W,~HLGREX, 1960; b y n e u t r o n a c t i vation). S t r o n t i u m : 13 p . p . m . (Prxso~- et al., 1953; b y e m i s s i o n s p e e t r o g r a p h y ) ; 12 p . p . m . (G,tsT, u n p u b l i s h e d ) . T e l l u r i u m ; 0.62 p . p . m . (Scm~'DEWOLF, 1960; b y n e u t r o n a c t i v a t i o n ) . T h a l l i u m : 0.0004-0.0038 (REED el al., 1960; b y n e u t r o n a c t i v a t i o n ) . T h o r i u m : 0.038 p . p . m . (BATE et al., 1959; b y n e u t r o n a c t i v a t i o n ) . U r a n i u m : 0.014 p . p . m . (HA.~rAOUCHI et al., 1957; b y n e u t r o n a c t i v a t i o n ) . V a n a d i u m : 98 p . p . m . (this p a p e r ; b y e m i s s i o n s p e c t r o g r a p h y ) . Y t t r i u m : 2.3 p . p . m . (this p a p e r ; b y e m i s s i o n s p e c t r o g r a p h y ) . Z i r c o n i u m : 28 p . p . m . (P~-so~- et al., 1953; b y e m i s s i o n s p e e t r o g r a p h y ) . N o t e a d d e d i n p r o o f : - - D e t e r m i n a t i o n o f t h e n o b l e m e t a l s b y c u p e l l a t i o n followed b y emission s p e c t r o g r a p h y ( a n a l y s t s : A. LSFanr.N, P. V s a n d H . B. W I I K ) g a v e t h e following r e s u l t s (all in p . p . m . ) : R u 0.060; l~h 0.064; P d 0.44; 0 s 0.16; I r 0-24i Pb 0.44; A u 0.04. Acknowledgements~Ve are indebted to the J. Lawrence Smith Fund of the National Academy of Sciences for a grant towards the cost of this investigation. ~Vo would also express our gratitude to Professor W. tt. l~E~u[ous~ and Mr. OrcA Jo~.Nstru for the use of the facilities of the spectrographic laboratory of the Geology Department oftho University of Chicago, to Dr. :H. S. YODER for assistance in the determination of the composition of the olivine b y X-ray technique, and to ~Ir. E. P. :HENDERSONfor critical reading of the manuscript.
~EFERE~CES AImENs L. H., PLXSON~V. H. and I ~ m N S ~I. ~I. (1952) Association of rubidium and potassium and their abundance in common igneous rocks and meteorites. Geochim.etGosmochim. Acta2, 229-242. BATE G. L., :HUIZENOAg. 1%. and I:~OTRATZ:It. A. (1959) Thorium in stone meteorites by neutron act;ivation analysis. Geochim. et Cosmochim. Acta 16, 88-100. BATE G. L., POTRATZ:H. A. and HulzE~xox ft. R. (1960) Scandium, chromium and europium in stone meteorites by simultaneous neutron activation analysis. GeocMm. et CosmocMm. Acta 18, 101-107. BOWEN lq. L. and Scm~.mv.n J. F. (1935) The system !~Ig0--Fc0--SiO e. Amer. J. Sci. 29, 151-217. :ED~VARDSG. and Unv.Y H. C. (1955) Determination of alkall metals in meteorites by a distillation process. OeocMm. et Cosmochim. Acta 7, 154-168. E r ~ I ~ W. D. and HULZENOAJ. R. (1959) Bismuth, thallimn and mercury in stone meteorites by activation analysis. GeocMm. et Cosmochim. Acta 17, 125-135. FL~.TCILERL. (1921) The meteoritic stone seen to fall near Crumlin, County AntrLm, on September 13, 1902. l]liner, l]lag. 19, 149-162. FooTv. W. ~I. (1912) Preliminary note on the shower of meteoric stones near Holbrook, Navajo County, Arizona, July 19, 1912, including a reference to the Pcrseid swarm of meteors visible from July 11 to August 22. A m e r J . Sci. 34, 437-456. GAST P. W. (1960) Alkali metals in stone meteorites. Geochlm. et CosrnocMrn. Acta. 19, 1--4. GEISS J. and HEss D. C. (1958) Argon-potassium ages and the isotopic composition of argon from meteorites. Astrophys. J. 127, 224-235. GORDONB. ~]'., FRIEDSIA-~L. and EDWARDS G. (1957) Caesium in stony meteorites. GeocMm. et GosmocMm. Acta 12, 170-171. 282
The Holbrook, Arizona, chondrit~) HAXtAaUCtIIH., REED G. ~V. and TU~KEvIClt A. (1957) U r a n i u m and barium in stone meteorites. Gcochim. et Cosmochim. Acta 12, 337-347. JEnE.~hm E. and S_~'~'I)nEAA. (1953) Sur la meteorite do Guidder. Geochlm. et Cosniochim. Acts 4, 83-88. K ~ o H. (1954) Study of orthopyroxenes from volcanic rocks. Amer. llIin. 39, 30-46. 3I~s~ R. R. and HESS D. C. (1958) Lead from some stone meteorites. J. Chem. -Phys. 28, 1258-1259. ~IAso.~ ]3. a n d ~VHK H. B. (1960) The ~liller, Arkansas, chondrite. Geochim. et Cosmochim. Acta. 21, 266-271. ~IER~mL G. P. (1912) A recent meteorite fall near Holbrook, Navajo County, Arizona. Smithsonian _~lisc. Coll. 60, No. 9. Pl,~so,'~ W. H., An~E~-S L. It. a n d FRA.','CKZI. L. (1953) The abundances of Li, Si, Sr, Ba, and Zr in chondrites a n d some ultramafie rocks. Gcochim. et Cosmochim. Acta 4, 251-260. POLDE~VA~LRT A. (1950) Correlation of physical properties and chemical composition in the plagioclase, olivine, and orthopyroxene series. Amer. ~lin. 35, 1067-1079. P1~Io~ G. T. (1916) The meteoric stoncs of LaImton, ~Varbreccan, Cronstad, Daniel's Kuil, Khairpur, and Soko-]3anja. ~llincr. 2llag. 18, 1-25. Palor~ G. T. (1920) The classification of meteorites. ~lIiner. ~llag. 19, 51-63. PItieR G. T. a n d ItEx" M. H. (1953) Catalogue of 2Ieteoritcs, with Special 1reference to those Rep. resentezl in the Collection of the British ~lluseum (Natural History). British ZIuseum, London. :REED G. W., K I a o s m K. and TU~KEVIOHA. (1960) Concentrations of some heavy elements in meteorites b y activation analysis. Geochim. et Cosmochira. Acta. 20j 122-140. SCm~;D~WOI~, V. (1960) Selenium and tellurium content of stony meteorites b y neutron activation. Geochim. et Cosmochim. Acta 19, 134-138 SOm~,~DEWOL~" U. and XVa_~L~RE.~ ~I. (1960) The rhodium, silver and indium content of some chondritic meteorites. Geochim. et Cosmochim. Acta 18, 36-41. T ~ . y It. C. and CnAIa H. (1953) The composition of the stone meteorites and the origin of the meteorites. Geochim. et Cosmochim. Acta 4, 36-82. IJREr H. C., 5IELE A. and ~IAYEDA T. (1957} Diamonds in stone meteorites. Geochirn. et Cosmochim. Acta 13, 1--4. UttEr It. C. and ZIAY~DAT. (1959) The metallic particles of some chondrites. Geochbn. et COSmochim. Acta 17, 113-124. ~VAnT~W. A. (1950a) A check on some previously reported analyses of stony meteorites with exceptional high content of salic constituents. Geochim. e~ Cosmochim. Acta 1, 28-32. ~VAHLW. (1950b) The statement of chemical analyses of stony meteorites and the interpretation of the analyses in terms of m i n e r a l s . . ~ l i n e r . ~llag. 29, 416-426. ~VEBSTER I~. K., ~IORGAI~T~. W. a n d S:~AL~S A. A. (1958) Caesium in chondrites. Geochim. e~ Cosmochim. Acta 15, 150-152. ~Vns: tI. ]3. (1956) The chemical composition of some stony meteorites. Gcochim. et Cosmochim. Acta 9, 279-289. YODER H. S. and SAHA.~t~ T. G. (1957) Olivine X-ray determinative curve. Amer. Min. 42, 472--491.
283