Pertinent general properties of the planets are listed. The condensation of the solar nebula is set in the context of stellar evolution and meteorites with sections on astronomical observations, chemical composition of the solar nebula, physical properties of the solar nebula, and chemical and physical aspects of condensation, accretion, and planetary differentiation. A cool nebula is preferred to allow survival of pre-solar grains with isotopic anomalies. Equilibrium progressive condensation of the solar nebula is regarded as a useful theoretical boundary, but complex processes involving crystal-liquid differentiation in, and collisions between, planetesimals are used to interpret the properties of meteorites and terrestrial planets. Chemical differentiation in the nebula begins with condensation and aggregation of dust, which can yield oxidized and reduced products depending whether C/O is less or greater than unity. Simple models for direct accretion of condensed materials into planets are reviewed but not adopted. Physical interactions involving small bodies include collisional accretion of dust-covered bodies, and differentiation of silicate and metal from mechanical, magnetic, and electrostatic forces. Physical and chemical differentiation involving large bodies involves head-on and glancing collision of planetesimals, orbital deflection, and disintegration within the Roche limit, and collision with debris rings and moons. Planetary accretion: dynamics, time scale, and heat sources involves more rapid growth of a larger body than a smaller one with ultimate development of one planet in each feeding zone, which flares out and ultimately overlaps with adjacent zones. Mars is small, and a planet did not develop in the asteroid belt, because of perturbations from Jupiter. The giant planets deflected material into the inner solar system. Melting of early planetesimals is invoked to explain differentiated meteorites. Chemical differentiation inside planet esimals and planets describes the phase equilibria for metal, sulphide, and peridotite, either dry, wet, or containing CO2. A wet body could begin crystal-liquid differentiation near 1250 K with sinking of Fe,S-rich liquid and rising of basaltic melt. The peridotitic residuum might undergo a subsequent differentiation at higher temperature under volatile-free conditions. Mineralogical storage of H2O, CO2, S, Cl, F, and alkalies is discussed. Chemical differentiation in planetary atmospheres briefly mentions escape of light species.

For the Earth, the early history is constrained by Archaean rocks dating from −3.8 × 109 yr whose properties indicate a non-reducing atmosphere, and a mantle that yielded volcanic rocks mostly similar to recent ones. The upper mantle (above 200 km depth) contains peridotitic rocks attributable to crystal-liquid differentiation and metamorphism. Volatile elements exist in mica and other minerals, but are sparse. Abundances of siderophile and chalcophile elements are high enough to require late accretion of material rich in these elements, the presence of a barrier between upper mantle and core, and some extraction by sinking sulphide. The mantle (deeper than 200 km) and core are inaccessible to direct study but interpretation of seismic data coupled with high-pressure laboratory studies requires inversion to dense phases in the mantle (especially perovskite?) and presence of light elements in the core (mainly S?). The bulk composition is modelled by cosmochemical analogy constrained by geophysical and geochemical parameters. The early condensate may be augmented by 1.5 ± 0.5? over (Mg+Si), and metal by 1.2±0.1?, while alkalies are probably depleted six-fold. Radial heterogeneity from a reduced interior to an oxidized exterior is suggested. For the Moon, sections cover observations, petrologic interpretations, and bulk chemical composition. For the origin of the Earth and Moon, age constraints, chemical constraints, and dynamical and accretional constraints allow comparison of suggested origins, with the conclusion that the Moon formed by either fission or disintegrative capture during early growth of the Earth, followed by simultaneous accretion coupled with disintegrative capture of planetesimals.

Mercury must be Fe-rich, but the silicate may not be just early condensate. For Venus, reviews are given of the surface properties, atmosphere, speculations on bulk composition and speculations on surface mineralogy and atmospheric compositions. The CO2 is in the atmosphere; most H may have been lost with concomitant oxidation of rocks; K/U ratios suggest basaltic and granitic rocks, and the high-surface temperature (c.740 K) implies granulitic metamorphism. For Mars, reviews are given of surface morphology, atmosphere and volatiles, mineralogy and petrology, and geophysical and geochemical models. Prolonged emission of Fe-rich lavas is suggested. Volatiles were removed by mineralogical processes from the atmosphere to give ice caps and sediments affected by aeolian processes and oxidation from photochemically generated H2O2. Fe-rich layer silicates, maghemite, and Mg-sul-phate may dominate the sediments.

The composition of comets and interplanetary dust may be inferrable from micrometeorites whose complex properties are suggestive of carbonaceous meteorites. Asteroids should be supplying at least many of the meteorites to Earth. A general description and review of remote-sensing studies culminate in a review of spatial descriptions and implications. The main belt is dominated by dark C-type asteroids assumed to be the primordial inhabitants produced by primary condensation and local accretion. The inner zone contains some brighter S-type asteroids interpreted as having undergone separation of metal from silicate as in stony-iron meteorites, as well as some E- and M-types perhaps matching enstatite-bearing meteorites and irons. Perhaps these differentiated(?) asteroids, as well as basaltic Vesta, are strays perturbed outwards from the inner solar system.

A review of meteorites covers carbonaceous meteorites, ordinary chondrites, enstatite chondrites and achondrites, reduced irons, forsterite-bearing meteorites and silicate inclusions in irons, irons, pallasites, chassignites and nakhlites, ureilites and lodranite, eucrites and shergottites, diogenites, howardites and mesosiderites, oxygen isotopes, and original location of meteorites. Emphasis is placed on mineralogical properties demonstrating crystal-liquid differentiation, brecciation, agglomeration, and even aqueous alteration and vapour transfer, though some evidence remains of direct condensation of gas to solid. The meteorites demonstrate the existence of many parent bodies (probably over 60), and most macrometeorites are ascribed to collision debris from the main-belt asteroids that has been deflected past Mars. The range of oxygen isotopes is explained by mixing of supernova debris rich in 16O with gas-solid differentiates of the nebula.

The culmination of the review is a suggested synthesis, which emphasizes a new model of heterogeneous accretion from planetesimals whose diverse compositions range from reduced material near Mercury to oxidized material from the asteroid zone outwards. Growth of a terrestrial planet begins from near-by slow planetesimals, and ends with distant fast planetesimals. Only the Earth and Venus are big enough to retain debris from late volatile-rich planetesimals deflected to high speed by the giant planets. Mercury, Moon, and Mars are volatilepoor. The Earth is zoned from a reduced interior, composed of crystal-liquid segregates of planetesimals captured early, to an oxidized exterior containing some material captured from outside the orbit of Mars. A mantle barrier hindered chemical equilibration. Hydrogen loss augmented oxidation. The mantle may be chemically zoned inwards from olivine-rich composition to pyroxene-rich composition, and the core should be reduced and contain substantial S and perhaps C and P. Mercury and Venus should have accreted reduced material, and only Venus should contain volatiles obtained from late planetesimals from outside the Martian orbit. Mars should have accreted mainly S-type asteroids, and have captured little volatile-rich material.

Rajite was found at Lone Pine, New Mexico, by R. A. Jenkins. It occurs as small (1.5 mm) crystals in rhyolite with mackayite, and may be a pseudomorph after teineite. Analysis gave CuO 18.4, 15.3, 18.0; TeO2 73.7, 79.8, 79.1; rem. (respectively) 7.9, 2.4, 2.3. Some CaO in samples 2 and 3: 2.5, 0.6%. This gives CuTe2O5, identical to the artificial compound prepared by Moret et al. (1969). Easily soluble in dilute acids; readily fusible.

Monoclinic P21/c with a = 6.866 Å, b = 9.314, c = 7.598, β = 109.1°. Strongest lines 3.064(10), 4.654(8), 3.348(8), 3.111(7), 2.744(7), 3.793(6B), 2.844(5), 2.796(5). With Z = 4, ρcalc = 5.77 g/cm3.

Crystals Duesbury green (RHS-131D), H = 4, ρmeas = 5.75 g/cm3. Pleochroic in greens γ > β > α; α = 2.115, β = 2.135, ‖ [010], γ = 2.26, α:[001] 22° in obtuse β, 2Vγ = 40°.

A new hydrated zinc aluminium phosphate mineral has the composition ZnAl2(PO4)2(OH)2.3H2O. It has been named kleemanite. It occurred rarely both as veinlets 1–2 mm thick, and as thin layers on surfaces of cracks and small cavities in one section of the iron ore deposit at Iron Knob, South Australia. Chemical, X-ray, thermal analysis, and optical data are given.

Georgeite, an amorphous copper carbonatehydrate, has been found in the oxidation zone of the Carr Boyd nickel deposit, Western Australia. It forms thin coatings mostly associated with malachite and chalconatronite on partly weathered tremolite rock containing disseminated copper and iron sulphides.

Physical properties: Colour light blue, streak pale blue, lustre vitreous to earthy, fracture conchoidal, soft, sp. gr. 2.55; transparent to sub-opaque (aggregates), n(NaD) = 1.593, isotropic. Amorphous to X-rays and electron beam.

Chemical microanalysis gave (wt%) CuO 54.9, ZnO 0.4, Na2O 2.7, CO2 20.8, H2O 21.7, sum 100.5. After deduction of all Na2O and corresponding amounts of CuO, CO2, and H2O as chalconatronite (12.35 wt%) the atomic ratios correspond to an empirical formula (Cu5.0, Zn0.05)(CO3)3(OH)4.12.6.3H2O, the ideal formula being Cu5(CO3)3(OH)4.6H2O.

Garavellite occurs in polished sections, as small aggregates, up to 200 µm across, of anhedral crystals, usually in direct contact with tetrahedrite, Sb-rich bismuthinite, chalcopyrite, and siderite. Chemical formula Fe0,80Cu0.02Sb1.13Bi0.78As0.01S4 on the basis of S = 4, or ideally FeSbBiS4.

The mineral has an orthorhombic unit cell with a = 11.439, b = 14.093, c = 3.754 Å, Z = 4; calculated density 5.64 gm/cm3. Important diffraction lines are 14.00 (m) 010, 7.08 (m) 020, 3.62 (vs) 230, 3.49 (m) 040, 3.34 (m) 320, 3.20 (vs) 121, 3.10 (m) 201, 2.98 (s) 240, 2.89 (s) 221, 2.63 (vs) 311, 2.51 (vs) 250, 2.16 (m) 421, 1.677 (m) 312. In reflected light it is grey with a brown-olive tint similar to that of tetrahedrite. Bireftectance is distinct and anisotropism is also strong, from yellowish-green to bluish grey. Vickers hardness (50 g load) 212–22 kg/mm2. Reflectance in air: 470 nm R1 = 33.5−34.7%, R2 = 40.5– 42.8%; 546 nm 32.8–34.7%, 40.2–42.0%; 589 nm 32.6– 33.7%, 39.3–41.0%; 650 nm 32.4–34.6%, 38.4–41.0%.

The mineral and name have been approved before publication by the Commission on New Minerals and Mineral Names, IMA.

Frigidite, the so-called nickel-bearing variety of tetrahedrite found at this locality, is shown to be an intergrowth of tetrahedrite and Ni-bearing minerals.

Ore specimens from the abandoned copper mine at Seathwaite Tarn, Cumbria, were studied in polished section by reflected light microscopy. The mineral paragenesis is described and related to current views on Lake District ore genesis. A common origin with the neighbouring deposit at Coniston is proposed. Wittichenite was identified in the ore, and is the first authenticated occurrence in Great Britain.

The wittichenite (BM 1977, 172) discovered in the course of a reflected light study of polished sections from the Seathwaite deposit, Cumbria (described earlier in this journal by Stanley and Criddle), is the first authenticated occurrence of the species in Great Britain; for this reason it was examined in detail and compared with a specimen (BM 1437) from Wittichen, the type locality. Chemical analyses, cell dimensions, visible-spectrum reflectances, quantitative colour values, and VHN's are provided. They are in agreement with previously published data for the species.

Losses of FeO, Na2O, and K2O from an alkali olivine basalt melted above the liquidus temperature in Pt80Rh20 wire loops are reported as a function of temperature, time, and PO2. Increasing temperature and decreasing PO2 increase the losses. Compared to open capsules the wire-loop container reduces FeO loss to a minimum but may exacerbate Na2O loss. Nonetheless for most types of experiment involving melt these losses are acceptable.

Losses of Fe and Na from a typical basaltic liquid during experiments using the wire-loop method have been determined for both Pt and Ag40Pd60 alloy wire by electron-microprobe analyses of the quenched glasses. The amount of Fe lost is dependent on the duration of the experiment and is particularly sensitive to the ratio of sample to metal in direct contact with it. Fe losses can be minimized by using the thinnest wire possible in conjunction with the largest amount of sample that will adhere to the wire and, if Ag-Pd wire is used, can be kept below the 1% level even in long experiments. Much more serious in terms of changes in the bulk composition are losses of Na, which appear to be in direct linear proportion to the length of the experiment and in inverse proportion to the mass of the sample. Even when samples in excess of 200 mg are used the Na losses are unlikely to be less than 5% except in experiments of less than a few days' duration or on samples with very low initial Na contents.

An undeformed metadolerite dyke cutting foliated pyroxene-granulite facies gneisses in the Jotunhelm, Norway, has almandine rods replacing the cores of plagioclase laths, although garnet is generally absent from the enclosing gneisses, and is not present in reaction zones between peridotites and gneisses. Chemical analyses of the dyke and its garnet, plagioclase, and clinopyroxene are given. The presence of garnet in the dyke is attributed to the low mg ratio of the rock. The nature of the reaction leading to garnet pseudomorphous after plagioclase is discussed.

Bohdanowiczite was first described in 1967 but incomplete data prevented its acceptance as a new mineral at that time. Additional data on the same material now characterize bohdanowiczite as a new species with the formula:

3[(Ag0.98Cu0.02)0.97(Bi0.97Pb0.03)1.02(Se0.83S0.17)2.01]

The mineral occurs in intimate intergrowths with clausthalite and wittichenite in polymetallic mineralization at Kletno in Poland. In reflected light bohdanowiczite has a creamy-yellow colour and short polysynthetic twinning is frequently observed. Cell parameters indexed on a hexagonal lattice are a = 4.183±0.008 Å and c = 19.561± 0.016 Å. Pm1 is the most likely space group. The strongest lines of the powder pattern are 2.91(100), 2.03(30), 3.40(20), 6.54(20), 2.09(18), 3.26(18). The calculated density is 7.72 gm/cm3 and the VHN between 63 and 96 kg/mm2.

Crystal-chemical analyses of the serpentine polymorphs, sampled from macroscopic veins in the serpentinite rocks from Sasso della Mantesca and Sasso di S. Zanobi, are reported. The samples were examined by X-ray diffraction, thermal analysis (TG and DTG), scanning and transmission electron microscopy, IR absorption spectroscopy, microprobe, and chemical tests.

The results show: chrysotile 2Orc1 in tubular fibrils placed perpendicularly to walls of iso-oriented ‘lenticular veins’; and polygonal serpentine formed by flat layers of lizardite 2H and/or 1T, arranged as an outer shell of a central core of chrysotile 2Mc1 fibres; this type of serpentine with high crystallinity and unusual morphological development is included in ‘green veins’, which show variable Al, Fe, and Mg contents.

A genetic mechanism correlating the petrographic observations with the mineralogical results is discussed.

The substitution of 2A13+ for Si4+ +M2+ (M = Mg or Ni) has been studied by infra-red spectroscopy in 7 Å trioctahedral minerals over the composition range from Al = 0.00 to Al = 2.00. Significant differences are observed in the infra-red spectra and these make possible an estimation of the amount of Al in tetrahedral coordination. The most striking effect of the substitution is observed in the stretching vibrations of the outer hydroxyl groups and that of the silicate anion.

The aluminous Mg-serpentines can be readily distinguished from their analogues, the aluminous Niserpentines, by the absence of the Mg-OH absorption band between 570 and 615 cm−1 in the latter.

The Verkhne Dnieprovsk material (BM 51183) in the collection of the British Museum (Nat. Hist.) is chemically group IIE and therefore distinct from Augustinovka. Structurally it is a finest octahedrite, with a kamacite band-width (0.05 mm) and bulk Ni content (Scott and Wasson, 1976) appropriate to a cooling rate of 830 K Myr−1. Subsequent pre-terrestrial shock has produced localized deformation and shock-heating effects, which include mm-size globules of metal-phosphide melt product with a dendritic texture indicating resolidification at c.10 000 K sec−1. It is suggested that the phosphides were already fissured at the time of shockmelting. The structure of Verkhne Dnieprovsk, although lacking silicates, is analogous to that of Kodaikanal.

The distribution coefficient KD = (Mg/ Fe)garnet/(Mg/Fe)biotite has been calculated for eight garnet-biotite pairs from rocks ranging from the garnet isograd to the staurolite zone along the Stonehaven coast of NE Scotland. This distribution coefficient depends upon metamorphic temperature and is not dependent upon the Mn and Ca content of garnet. Garnet-biotite geothermometer yields temperatures of about 500, 550, and 575–620°C for the garnet, chloritoid + staurolite, and staurolite zones respectively.

The mineralogy and major-element geochemistry of thirty-seven samples from a borehole in the Upper Cretaceous Chalk (Santonian) of Kent has been determined. The mean carbonate content is 97% and the carbonate is a low-Mg calcite (0.42 mol % MgCO3). Most of the silica is deduced to be biogenic chert. The total clay content probably varies through the sequence due to changes in the rate of carbonate sedimentation. The clay composition remains relatively constant with smectite more abundant than illite. The smectite and K-feldspar could be formed from volcanic debris whereas illite and quartz are thought to be detrital.

The crystallization history of four trondhjemite samples from the Scourian complex, NW Scotland, has been investigated using composite ilmenite-magnetite grains. A variety of compositions are present both as large- and small-scale exsolution lamellae, which can be used to unravel the complex cooling history of these rocks. The samples were collected near Upper Badcall, Sutherland, where intrusive trondhjemite sheets 1–2 m thick cut banded gabbro. The trondhjemites have a complex history that includes four stages: magmatic intrusions, granulite facies metamorphism, hydration and retrogression to amphibolite facies, and slow cooling with uplift.

Ilmenite-magnetite grains in samples HR. 49, 53, 86 display a complex exsolution pattern (fig. 1A). An original titanomagnetite exsolved into large-scale (up to 50 µm wide) ilmenite-magnetite lamellae from which have subsequently exsolved small-scale lamellae (c.4 µm wide) parallel to the earlier lamellae. The ilmenite-magnetite pairs form subhedral grains in a granoblastic aggregate of plagioclase and quartz. A little biotite overgrows some oxide grains. Ilmenite-magnetite grains in sample HR. 56 are composed of broad-zoned lamellae (fig. 1B); small-scale exsolution lamellae are absent. Silicate-grain boundaries are irregular and lower-temperature minerals (chlorite and carbonate) are more common.

The experimental results of Buddington and Lindsley (1964) allow the equilibration temperature and oxygen fugacity of coexisting ilmenite and magnetite to be determined from their chemical composition. Subsequent workers have shown that it is possible to determine liquidus temperatures and oxygen fugacity for volcanic rocks (Carmichael, 1967; Anderson, 1968a). Slowly cooled igneous and metamorphic rocks, however, have continued to equilibrate below their solidus and show a range of temperatures and oxygen-fugacity conditions (Anderson, 1968b; Duchesne, 1972; Oliver, 1978; Bowles, 1976, 1977).

This paper presents 42 new pairs of analyses made by electron-probe microanalysis, from 13 composite ilmenite-magnetite grains (Table I). Mole % ulvöspinel and R2O3 values have been calculated using the method of Carmichael (1967) and used to determine temperature and oxygen fugacity at equilibration, from the experimental data of Buddington and Lindsley (1964).

By using a scanning electron beam it is possible to obtain the average composition of a broad lamella that contains smaller exsolution lamellae in order to estimate its composition prior to exsolution. A −log10ƒo2ν.T °C plot of lamellae whose original composition has been determined in this way shows that they lie on a curve slightly above the Ni-NiO buffer between 1010 and 850 °C (fig. 2). Temperatures of the order of 1000 °C are probably magmatic temperatures since they are higher than is normally recorded for granulite-facies metamorphism; 850 °C is interpreted as the blocking temperature below which diffusion was unable to occur to form large-scale lamellae. A comparison may be made between this oxygen-fugacity curve and the curves determined by Carmichael (1967) (fig. 2) for acid lavas coexisting with different phenocryst phases. If an adjustment is made for the differences in bulk composition and pressure, some correspondence between the analysed points and the curve for hydrous silicates would be expected since hornblende is the earliest Fe-bearing silicate seen in the trondhjemite. However, correspondence is not found, implying that amphibole did not control the oxygen fugacity, either because it was not the main Fe-bearing phase at magmatic temperatures, or because the oxygen fugacity was externally controlled.

After the formation of broad high-temperature lamellae Ti diffusion continued on a smaller scale (2–3 µm) so that the lower-temperature history of these grains can be considered in terms of many independent microsystems. Limited diffusion continued across the boundaries of and within early magnetite and ilmenite lamellae. The compositions of small-scale exsolution lamellae in ilmenite and magnetite hosts have been determined. Lamellae of ilmenite in magnetite from different grains define separate log ƒo2-T curves for different grains. Lamellae of magnetite in ilmenite equilibrated at lower temperatures and oxygen fugacities. Individual microsystems have equilibrated at different temperatures and oxygen fugacities within the same grain and similar microsystems in different grains have equilibrated at different temperatures and oxygen fugacities, suggesting that the rock itself has become a series of independent closed systems.

The compositions of phases either side of early high-temperature lamellar boundaries have been measured. Analyses from different rocks yield different oxygen-fugacity curves in the same temperature range (765 to 610 °C). Higher temperatures were obtained for grains 49/3 and 86/4, which have exsolved into broad-zoned lamellae with no small-scale exsolution. The sense of the zoning is such that R2O3 in ilmenite decreases as it approaches magnetite. The equilibration temperature and ƒo, at the grain boundary increases from the centre of the grain to the edge.

In HR. 56 ilmenite magnetite grains show broad-zoned lamellae with no late small exsolution lamellae. The sense of zoning is such that magnetite grains increase in ulvöspinel content towards ilmenite and ilmenite decreases in R2O3 towards magnetite (fig. 1B). Even though the grains are in disequilibrium, it is assumed that equilibrium was at least established close to the boundary between lamellae. Equilibration temperatures thus obtained are between 410 and 430 °C at an ƒo2 between the Ni-NiO and QFM buffers. Ilmenite-magnetite grains coexist with a biotite richer in Ti and a hornblende depleted in Fe relative to those in samples yielding higher oxide temperatures suggesting that there was continuous Fe-Ti exchange between oxides and silicates as well as between ilmenite and magnetite.

Zektzerite and its isotypes with Zr4+ replaced by Ti4+ or Sn4+ are readily synthesized by fusion of the constituent oxides at 1550 °C followed by recrystallization of the melt or quenched glass at 750–850 °C and I bar pressure. Indexed powder X-ray data for synthetic zektzerites are presented in miniprint Table I. The powder patterns are consistent with an A-centred orthorhombic symmetry. Refined cell dimensions are given in Table III.

The Ti, Zr, and Sn zektzerites melt incongruently. Table IV records melting-point data. The coefficients of thermal expansion of Zr and Ti zektzerite have been determined by X-ray dilatometry. Both have moderately low coefficients of expansion: numerical values are given in miniprint Table II.

Zektzerites contain a six-repeat unit doublechain silicate anion. Although they are chemically similar to milarites, the latter contain double-ring Si12O30 anions. Despite the difference in anion constitution both have structures in which many chemically similar atoms occupy similar positions. The effect of this similarity on the physical properties (e.g. X-ray powder pattern) is enhanced by the similar size and shape of their orthorhombic unit cells. The presence of vacant sites in zektzerite that are potentially available for cation occupancy suggests that chemically complex substitutions may occur; for example LiNa2ScSi6O15 has been synthesized and is believed to be isostructural with zektzerite and emeleusite, LiNa2FeSi6O15.

Colourless, purple, and pink topaz and transparent quartz crystals have been found in calcite veins (with or without milky quartz) in calcareous rocks near Katlang (34° 24′ N, 72° 6′ E), Mardan district. The veins do not contain any fluorite nor the country rocks any topaz. The topaz and transparent quartz crystals are mostly broken and perfectly euhedral outlines are very rare. Refractive indices, 2V, specific gravity, and the fluorine (determined) and H2O + (calculated) contents of two topaz crystals are suggestive of their high 100 OH/(OH+F) ratios (> 25). Rather than being derived, the topaz may have formed in situ by hydrothermal/pneumatolytic activity, followed by tectonic movements that fractured the crystals and resulted in their incorporation in later-formed vein calcite.