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Download the Scanned THn AMERrclr.l M rNERALocrsr JOURNAL OF THE MINERALOGICAI SOCIETY OF AMERICA Vol. 52 MARCH_APRIL, 1961 Nos. 3 and 4 EXTRATERRESTRIAL MINERALOGY1 Bnrarq Masow, U. S. National Museum, Washington,D. C. In looking over the list of my illustrious predecessorsin the position of president of this society, I am intrigued to see that only two were museum curators (although some were university professorswho were also curators of extensive collections). The last curator to stand in my present shoeswas William F. Foshag in 1940, and his presidential ad- dress was entitled "Problems in the study of meteorites." Coming from the same institution, I feel it is not inappropriate to follow his good ex- ample, and to provide you with some account of the recent progress of meterorite mineralogy. Although the obvious minerals of meterorites were recognized quite early, the study of the most abundant (and mineralogically complex) meteorites, the chondrites, was not possibleuntil the introduction of the polarizing microscopeabout 100 years ago. The techniquesof microscopic petrology were applied to stony meteorites originally by Sorby, who published a paper on this subject in 1863. The fortunate conjunction of a first-rate microscopist, Gustav Tschermak, and the outstanding mete- orite collection of that day, the Vienna collection, resulted in a classic monograph on the mineralogy and petrology of meteorites, Tschermak,s "Die mikroskopischeBeschaffenheit der Meteoriten," publishedin 1885. This remarkable work, long unavailable except in a few libraries, was recently republished, in facsimile, with an English translation by Wood (1964).In it Tschermakrecognized sixteen minerals occurring in meteor- ites. Table 1 traces the development of meteorite mineralogy over the following seventy years. It can be seen that the list grew very slowly. It is of interest to note that serpentinefirst appearsin Krinov's 1955list, al- though it is a major phasein some of the carbonaceouschondrites. Sulfur as a mineral is not recorded in any of the lists in Table 1, although Wcihler in 1860 extracted sulfur with alcohol from the Cold Bokkeveld meteorite, and later investigators extracted it from other carbonaceous 1 Presidential Address, the Mineralogical society of America. Delivered at the 47th Annual Meeting of the Society, November 15,1966, San Francisco, California. 307 308 BRIAN MASON T,rnr-n 1. Tnr MrNnnar-sor Mnrronttos, Ur :ro 1955 l'qrrino-- Tschermak'.." Hcide Krinov Mineral Irormula 188.s 19i4 1955 1915 Kamacite (Fe, Ni) x x x Taenite (r'e, Ni) X x x Copper (,u X Diamond C KX x Graphite C x Moissanite SiC XX X Cohenite FegC KX x *Schreibersite (Fe, Ni)rP x XX x +Osbornite TiN x X 'Iroilite FeS XX x *Oldhamite CaS x XX *Daubreelite IieCrzSr x XX x +Lawrencite (F'e,Ni)Cl: XX Magnesite (Mg, Fe)COr X X Calcite CaCOs x Magnetite Feroa X x x Chromite F eCr:O+ X X x Quartz SiOz x X x Tridymite SiOz X x x Chlorapatite Car(POr)sCl X X x Merrillite Car(PO+)z x x (Whitlockite) Olivine (Mg, Fe)zSiO+ X x X X Orthopyroxene (Mg, l'e)Sio: x X X Clinopyroxene (Ca, Mg, Fe)SiO; x X x x Plagioclase (Na, Ca)(Al, Si)+Os x X X X Serpentine (Mg, Fe)oSirOro(O,OH)s x *(An asterisk indicates those not known to occur in terrestrial rocks ) chondrites. Apparentiy these reports were discounted, or the sulfur ascribed to terrestrial weathering. In 1955, therefore, to specializein meteorite mineralogy might well have beenconsidered the refugeol alazy mineralogist onecould confine one'sactivities to lessthan thirty minerals out of the some 1500species recognized!The situation has changedrather radically sincethen, as is illustrated in Table 2.The number of meteoriteminerals has more than doubled in the last ten years.This remarkableupswing can be ascribed to two distinct factors: firstly, the greatly enhancedinterest in outer space,and an appreciationof the signifi.canceof meteoritesas the only extraterrestrialsamples we )'et have; and secondly,the application of F:,XT RA TTI,RREST RI A L M I N ]'RA LOGY 309 'Ieern 2. MrNnnars ol Mrrnonrrps Dnscnrepo SrNcr 1955 Mineral Formula Reference Sulfur S DuFresne and Anders, 1962 +Perryite NisSi Fredriksson and Henderson, 1965 Mackinawite FeS El Goresy, 1965 Pyrite FeSz Ramdohr, 1963 Sphalerite ZnS Ramdohr, 1963 Alabandite (Mn, Ife)S Dawson et a1., 1960 +Niningerite (Mg, F'e)S Keil and Snetsinger, 1967 Pentlandite (Fe, Ni)eSs Sztrokay, 1960 Cubanite CuFe:Ss Ramdohr, 1963 (Chalcopyrrhotite) Chalcopyrite CuFeSz Ramdohr, 1963 Valleriite CuFeSz Ramdohr, 1963 *T) ip rfichp'i t. K:CuFerzSu Fuchs, 1966 *Gentnerite CusFerCrrrSrs El Goresy and Ottemann, 1966 Cristobalite SiOz Dawson et al , 1960 Rutile TiOz Buseck and Keil, 1966 Ilmenite FeTiO: Yudin, 1956 Spinel MgAlrOo Sztrokay, 1960 *Sinoite Si,N,O Anddrsen et al , 1964 Dolomite CaMg(COa): DuFresne and Anders, 1962 Gypsum CaSO+.2HuO DuFresne and Anders, 1962 Epsomite MgSO+.7HzO DuFresne and Anders, 1961 Bloedite NarMe(SOa)r.4HrO DuFresne and Anders, 1962 +!-qrrinofnnitp Mgr(POa)z DuFresne and Roy, 1961 Graftonite (Fe, Mn):(POdz Olsen and Fredriksson, 1966 Sarcopside (Fe, Mn):(POa)z Olsen and Fredriksson, 1966 *Panethite NauMgz(PODz Fuchs et al.,1966 *Brianite NazMgCa(POdz Fuchs et a1.,7966 *Stanfieldite M93Ca4Fe2(PO4)6 Fuchs, 1967 Zircor' ZrSiOt Marvin and Klein, 1964 Ureyite NaCrSizOe Frondel and Klein, 1965 *Merrinueite (K, Na):IresSirzOso Dodd et al., 1965 *Roedderite (K, Na)zMgsSirzOso Fuchs et a1.,1966 Richterite NazCaMgsSisOz(OH, F), Olsen, 1967 x Not known to occur in terrestrial rocks. new and improved instruments and techniques-the reflecting micro- scope,X-ray diffraction, and the electron-beammicroprobe. Most of the meteorite minerals recognized in the past ten years are trace constituents,present in amounts usually much lessthan 1 percent. For example, the abundance of zircon in the vaca Muerta meteorite is estimatedto be about 0.002percent (Marvin & Klein, 1964).Neverthe_ less, the significanceof a particular mineral is in no way determined by 310 BI?IAN MASON 'I'anrr 3.'I'nn Cr-essrrrcATroNoF Mnrnonrtrs (rrcunns IN PARENTHESES ARI' TIIE NUMBERS OF OBSERVED FALLS IN EACH cress) Group Class Principal minerals Chondrites Enstarite (11) Enstatite, nickel-iron Olivine-bronzite (227) Olivine, bronzite, nickel-iron Olivine-hypersthene (303) Olivine, hypersthene, nickel-iron Carbonaceous (31) Serpentine, oiivine Achondrites Aubrites (8) Enstatite Diogenites (8) Hypersthene Chassignite (1) Olivine Ureilites (3) Olivine, clinobronzite, nicliel-iron Angrite (1) Augite Nakhlite (1) Diopside, olivine Eucrites and howardites (40) Pyroxene, plagioclase Stony-irons Pallasites (2) Olivine, nickel-iron Siderophyre (1)* Orthopyroxene, nickel-iron Lodranite (1) Orthopyroxene, olivine, nickel-iron Mesosiderites (6) Pyroxene, plagioclase,n ickel-iron Irons Hexahedrites (7) Kamacite Octahedrites (32) Kamacite, taenite Ni-rich ataxites (1) Taenite * Find its abundance.A mineral is abundant becausethe elementsforming it are abundant, and the mineral itself has an extensivestability field. In prac- ticaily ali meteoritesthe elementsFe, Mg, Si, and O make up over 90 percent, both in weight and in number of atoms; hence the common minerals are metallic nickel-iron (as kamacite and taenite),olivine, orthopyroxene, and calcium-poor clinopyroxene. A rare mineral is rare either becauseit containsa rare element,or becauseit has a very limited stability field. A mineral reflecting the latter situation is of especialsig- nificancel it may enable us to deduce the conditions of origin of the meteoritefar more preciselythan could be establishedfrom the common minerals.Since one of the principal objectivesof meteoriteresearch is to determine the conditions under which theseenigmatic bodiescrystallized, the study of these rare minerals should be particularly rewarding' For the benefit of those of you who have but a nodding acquaintance with meteorites, I wili include at this point their current classification (Table 3). It is a mineralogical-structural classification similar in prin- ciple to that used for igneous rocks. I would direct your attention to the very uneven population of the different classes-some are representedby a single meteorite, others by several hundred. EXTRATERRESTRIALMINERAI,OGY 311 This distribution suggeststo me that, in attempting to establish a coherentpicture of meteorite genesis,we are in effect working on a jig- saw puzzlewith many pieceslacking. The octahedritesdominate among the irons, the olivine-bronzite and olivine-hypersthenechondrites (some- times called jointly the common or ordinary chondrites) among the stones. Actually, in terms of observed falls, the chondrites are far more abundant than all other meteorites-chondrites, 8,1.6percent; achon- drites,8.0percent; stony-irons,1.6 percent; irons,5.8 percent. Few irons are seento fall; most are found and recognizedby the unique features distinguishing them from terrestrial rocks. A few years ago (Mason, 1962) I wrote an account of the meteorite minerals known at that time. I intend to take the opportunity provided today to update this account. Not all the minerals listed in Tables 1 and 2 will be discussed,but only those for which significant new data are available, or additional information not included in the referencesgiven for the minerals in Table 2. I shail also give a brief account of those minerals formed in meteorites by interaction with the terrestrial environ- ment. For conveniencethe material will be discussedunder the followine headings: The dominant silicate minerals Minor and accessoryminerals Doubtful and incompletely described
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