Rare-earth distribution has been determined for fourteen niobatetantalates containing essential rare earths. Those minerals with more than about 15 % TiO2 (and corresponding to either priorites or members of the euxenite-polycrase series) have Yt as the dominant rare earth with the heavier lanthanons in excess of the lighter lanthanons. Those minerals with less than about 4 % TiO2 and less than about 30 % (Yt,Ln)2O3 (and corresponding to samarskites) also have Yt as the dominant rare earth but they show a marked concentration of Gd + Tb + Dy over the other lanthanons. It is tentatively suggested that this power of selective lanthanon enrichment may be characteristic of samarskite among the niobate-tantalates examined.

The immediate object of the present paper is to place on record the history and characters of several Atacama meteorites of which no description has yet been published; but incidentally it is convenient at the same time to consider the relationship of these masses to others from the same region, which either have been already described, or at least are stated to be preserved in one or more of the known Meteorite-Collections.

The rock-specimens collected during the Antarctic Expedition of 1839-43 were deposited in the British Museum. A few years ago, in the course of a re-arrangement and registration of the rock-specimens n the Museum, this collection amongst others was examined, and microscopic sections of some of the specimens were prepared. Nothing, however, was published at that time, since it was found that the greater part of the collection had been practically duplicated by the rocks of the Challenger Expedition, which had a year or two previously been deposited in the Museum, and it was felt that mere petrographical descriptions of specimens have but little to recommend them in the absence of geological data as to the mode of occurrence and mutual relations of the rocks in the field.

Of the garnet group of minerals, two members only appear to have been synthesized from artificial melts, viz. melanite (L. Michel, 1892) and spessartine (L. Bourgeois, 1883, and A. Gorgeu, 1883); though grossular is once reported by E. S. Shepherd, G. A. Eankin, and F. E. Wright (1909) as being produced by reaction under pressure of calcium orthosilicate and aluminium chloride. In dry melts, pyiope is represented by a cordierite-forsterite-spinel assemblage, but no data are yet available to indicate the dry melt assemblages representing almandine. The home of almandine in sediments is the dynamically metamorphosed pelite, and its widespread regional occurrence in these crystalline schists implies a ready synthesis under the influence of shearing stress.

Previous work has established that natural ‘low-temperature’ intermediate plagioclases show single-crystal diffraction patterns in which the subsidiary reflections are split into two; the separation of these split reflections appears to be dependent on the composition of the felspar. Several of these specimens have been subjected to varying heat treatments and their diffraction patterns examined.

It is found that over the whole composition range the split subsidiary reflections have disappeared after treatment at high temperatures, and only the principal felspar reflections, which are characteristic of an albite-like structure, remain. Natural specimens initially showing anomalous patterns can also be homogenized in this way by suitable heat treatments. A careful study of the mode of disappearance shows that the separation of the subsidiary reflections is unchanged as long as they remain visible.

The structural and petrological implications of this work are discussed.

We present a dust flux (g m-2yr-1) record for the East Mediterranean Sea constructed using 87Sr/86Sr ratio measurements on the fine fraction of carbonate-free sediment from core 9501 from the north Levantine basin. The Saharan dust flux profile shows a first order correspondence with Atlantic dust-flux records in showing: (1) small dust fluxes during the last glacial maximum, a dust pulse associated with the Heinrich 1 (H1) event; (2) a small peak corresponding with the younger dryas (YD); (3) a decrease during the African Humid Period (AHP); and (4) an abrupt return to dustier conditions between ~5.7—5.2 ky BP.

Anandite is a new barium iron silicate found in the magnetite ore zone of the Wilagedera iron ore body, in the North Western Province of Ceylon. The mineral is named after the late Dr. Ananda Coomaraswamy, the first director of the Mineral Survey of Ceylon.

Anandite is monoclinic, with a 5·412, b 9·434, c 19·953 Å, β 94° 52′, space group C2/c. D 3·94, hardness 3–4. Optically positive, b ‖ β, γ ∧ a 12°, β 1·855, γ > 1·88. Pleochroism: β green, γ brown. Chemical composition corresponds to the simplified formula (Ba,K) (Fe,Mg)a (Si,Al,Fe)4O10 (O,OH)2 with Z = 2. The data available indicate that the mineral has the trioctahedral structure of the brittle micas.

There is a close optical and chemical resemblance between chamosite, the chloritic mineral of the bedded ironstones, and daphnite, a low-temperature vein-chlorite common in some of the Cornish tin mines. New material has made it possible to undertake a fresh comparison of the two minerals: chemical analyses have been made by Mr. C. O. Harvey, chemist to H.M. Geological Survey, and a report on the X-ray measurements is contributed by Mr. F. A. Bannister, of the Mineral Department of the British Museum.

The new analysis of chamosite agrees with the simple formula previously assigned: X-ray examination of material from several localities has now established the distinctive crystalline nature of this fine-grained mineral, which differs structurally from ordinary chlorites such as clinochlore. Daphnite, on the other hand, has the ordinary chlorite structure, but the new analysis fully confirms Tschermak's original opinion that it cannot be represented chemically as a mixture of serpentine and amesite.

A new occurrence of kornerupine in the skarn zone at Mautia Hill, Tanganyika, has yielded unit-cell dimensions a 16·100, b 13·767, c 6·735 Å, density 3·297, and composition Na0·01Mn0·01Ti0·02Mg3·69Fe0·37IIIAl6·36Si3·71B0·41O21·75(OH)0·25. The unit-cell clearly contains 88 anions rather than the 86 proposed previously. Grandidierite from Sakatelo, Madagascar, has unit-cell dimensions a 10·978, b 10·335, c 5·760 Å, space group Pna21 or Pnam, density 2·976, and composition Fe0·12IITi0·01Mg0·88Fe0·03IIIAl3·00Si1·00B0·97O9·00. The unit-cell contains 36 anions and the structure appears to involve A106 chains parallel to the c-axis.

Professor Arthur Holmes has described in the preceding paper a suite of rocks from Mafuru, Uganda. During his study he observed in thin section a mineral which in optical properties is indistinguishable from nepheline. He gives chemical evidence, however, for the presumption that a potassium aluminosilicate is present in mafurite which would suggest either that the nepheline-like mineral is kaliophilite or a polymorphous form of KAlSiO4. Kaliophilite is not isomorphous with nepheline, but has similar optical properties, and the two minerals could be easily confused in thin section. They may, however, be rapidly distinguished by X-ray methods. Even minute grains insufficient for chemical analysis can be determined with certainty; so it seemed probable that an X-ray study of the nepheline-like mineral from Uganda would give additional information and decide whether or no a separation and chemical analysis of the mineral should be attempted. Professor Holmes accordingly invited me to examine his specimens and rock-sections.

Gahnite and columbite with compositions (Zn5.96Fe1.55Mg0.21Mn0.13)Σ7.85Al16.09O32 and (Nb7.36Ta0.60Mn2.95Fe0.98Ti0.09)Σ11.98O24 occur as accessory phases in a highly evolved garnetiferous muscovite alkalifeldspar granite. Both phases have developed as a result of a concentration of Zn, Nb, and Ta during the fmal stages of the fractional crystallization which led to the formation of the pluton, and the lack of a major mafic mineral such as biotite, in which these elements are normally camouflaged in granitoid rocks.

Cannonite, ideally Bi2O(OH)2SO4, is a new mineral from the Tunnel Extension mine, Ohio Mining District, Marysvale, Utah, USA. It occurs mostly as intergrown crystalline aggregates (<1 mm) of subhedral to euhedral equant to prismatic crystals (<200 μm) in cavities in quartz gangue. Other associated minerals are cuprobismutite, bismuthinite, and covelline. Cannonite is colourless and transparent with an adamantine lustre and white streak. It is brittle with an uneven to conchoidal fracture. In reflected light it is low reflecting, weakly to moderately bireflectant and weakly anisotropic. Internal reflections (colourless to white) are abundant. Measured reflectance values in air and oil are tabulated. Colour values relative to the CIE illuminant C for R1 and R2 in air respectively are: Y% 10.4, 11.7; Lambdad 475,475; Pe% 2.6, 3.0. Calculated refractive indices at 589 nm: R1 1.91 and R2 1.99. VHN100 229 (range 183-280); calculated Mohs hardness is 4.

X-ray studies show that cannonite is monoclinic with space group P21/c and a 7.700(3), b 13.839(6), c 5.686(2) Å, β 109.11(3) ° It has a cell volume of 572.5(4) Å3 with Z = 4. Dcalc. is 6.515 g/cm3. The strongest six lines of the X-ray powder pattern are [d in Å (I) (hkl)] 3.206 (100) (221); 1.984 (90) (340, 152); 2.924 (70) (131); 3.644 (60) (111); 3.466 (60) (040); 2.782 (50) (112). Averaged probe analyses gave the empirical formula Bi1.99O(OH1.04)2S0.99O4 on the basis of 7 oxygen atoms. The name is for Benjamin Bartlett Cannon of Seattle, Washington, United States of America.

Miargyrite is the low-temperature monoclinic derivative of a high temperature cubic galena/halite structure. The essential features of its crystal structure (Knowles, 1959) were confirmed, but the details of the bonding changed [new space group C121; a 12.824(1), b 4.4060(3), c 13.193(1) Å, β 98.567(6)°]. The octahedral connectivity of galena/halite is severely distorted: Ag(1), 2S each at 2.53, 2.66 & 3.39 Å; Ag(2), 2 each at 2.54, 2.62 and 3.44; Ag(3), 2.38, 2.40, 3.05, 3.05, 3.53, 3.58; Sb(1), 2.45, 2.50, 2.51, 3.22 3.28, 3.41; Sb(2), 2.45, 2.50, 2.51, 3.22, 3.28, 3.41. The short distances define the following coordinations: very distorted tetrahedral Ag(1) and (2); near-linear Ag(3) at 178.9(2)° trigonal-pyramidal Sb(1) and (2) at 92.0, 93.6 and 96.8°. The ten shortest S-S distances range from 3.61 to 3.77 Å.

Felsic volcanic rocks exposed in the Frasnian Gafo Formation, in the Azinhalinho area of Portugal, display very similar geochemical signatures to volcanic rocks from the Iberian Pyrite Belt (IPB). located immediately to the south. The similarities include anomalously low high field-strength elements (HFSE) concentrations, possibly caused by low-temperature crustal melting, which translate into classification problems.

A geochronological study, using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses of zircon grains from these rocks, has provided concordia ages of 356±1.5 Ma and 355±2.5 Ma for two samples of rhyodacite porphyry, and 356±1.4 Ma for a granular rhyodacite. These results show that volcanism at Azinhalinho was broadly contemporaneous with IPB volcanism, widely interpreted as being of Famennian to Visean age. Considering that the host rocks of the Azinhalinho volcanic rocks are Frasnian, and therefore deposited synchronously with the Upper Devonian Phyllite-Quartzite Group sedimentation in the IPB basin, the radiometric ages imply that the Azinhalinho felsic rocks are intrusive and likely represent conduits or feeders to the volcanism of the IPB.

Exsolved garnet, sometimes associated with exsolved amphibole and zoisite, is abundant in aluminous clinopyroxene of garnet clinopyroxenite and clinopyroxenite xenoliths in the early Cretaceous dioriticmonzodioritic intrusions from the Xuzhou region, ∼100 km west of the Sulu ultrahigh-pressure (UHP) metamorphic terrane in eastern China. In addition to the mineral exsolutions, intergranular fine-grained garnet, zoisite, titanite, and sometimes amphibole are also present around the primary clinopyroxene grains. Clinopyroxene shows compositional gradients, with decreasing Al and increasing Si and Mg, adjacent to the garnet lamellae and intergranular garnet. In contrast, the exsolved and intergranular garnet is homogeneous in composition and typically more grossular-rich and pyrope- and almandinepoor than the coarse-grained primary garnet. The estimates of P and T for the precursor assemblage and garnet exsolution suggests a decrease of temperature from ∼950—1100ºC down to 620—780°C, and a nearly constant pressure from ∼15—20 kbar to 18 kbar, which are comparable with the metamorphic conditions of the associated eclogites. Therefore, garnet exsolution in garnet clinopyroxenite and clinopyroxenite xenoliths could be caused by high-pressure (HP) metamorphism. SHRIMP zircon U-Pb dating for the associated eclogite and gneiss xenoliths and Sm-Nd whole rock-garnet dating for the same eclogite demonstrate that parts of lower crust on the southeastern margin of the North China craton might be involved in the Triassic HP metamorphism due to the deep subduction of the Yangtze craton.

Kutnohorite with moderate and bright orange-red cathodoluminescence (CL) was studied by CL microscopy and spectroscopy. This mineral was found in fossiliferous concretions composed mainly of rhodochrosite from the Mn-carbonate mineralization at Úrkút, Hungary. The CL microscopy reveals that kutnohorite occurs as impregnations, layers and veinlets. X-ray diffraction, infrared spectroscopy and electron microprobe studies indicate that the luminescent kutnohorite has excess Ca (72.9–80.0 mol.% CaCO3, 16.3–20.5 mol.% MnCO3, 3.3–5.6 mol.% MgCO3 and 0.0–0.5 mol.% FeCO3). Transmission electron microscopy shows that the luminescent carbonate has a dolomite-type structure, with modulated and mosaic microstructures. The CL spectra of this Ca-rich kutnohorite have a single emission band at 630 nm that is characteristic of Mn2+ substitution in the structure. Our results provide evidence for moderate-to-bright cathodoluminescence of Mn-rich natural carbonates even at 8–10 wt.% Mn and up to 2400 ppm Fe. The self-quenching of Mn appears incomplete in the case of Ca-rich kutnohorite from Úrkút.

The paper investigates trace elements and crystal-rich fluid inclusions in spodumene from rare-metal pegmatites of the Kolmozero lithium deposit in the Kola region, Russia. The main lithium mineral in the pegmatites is spodumene, which occurs in three generations, designated as Spd-I, Spd-II and Spd-III. Iron, Na and Mn are the most typical element impurities in spodumene. The Fe/Mn ratio is 7.1 in Spd-I, 12.3 in Spd-II and 13.2 in Spd-III. Spd-II contains fluid and crystal-rich fluid inclusions. The crystal-rich fluid inclusions in Spd-II originally trapped CO2-bearing aqueous fluids with dissolved alkali carbonates. The crystal-rich fluid inclusions contain zabuyelite (Li2CO3) and cristobalite (SiO2) as solid phases, which have not been reported previously from the Kolmozero rare-metal pegmatites. These minerals are assumed to have resulted from a reaction between a CO2-bearing aqueous fluid and host Spd-II and are not related to the mineral-forming system of pegmatites.

Chromian tourmaline, in association with other Cr-bearing minerals (amphibole, mica, epidote, chlorite, titanite, rutile and chromian spinel), occurs in fine calc-schist levels within metacarbonate rocks from the Nevado-Filabride Complex, SE Spain. Electron microprobe analyses of tourmaline and coexisting minerals document both chemical differences dependent on the host-rock type and an irregular distribution of Cr at grain scale. Tourmaline is Na-rich dravite, with average Mg/(Mg+Fe) ratios of 0.83 and 0.63 a.p.f.u. and Cr contents of 0.32 and 0.18 a.p.f.u., in dolomitic and ankeritic marbles, respectively. Tourmaline contains small but significant concentrations of Zn (av. 0.01 a.p.f.u.) and in ankeritic marble it also contains Ni (av. 0.04 a.p.f.u.). Zn-rich chromian spinel appears as small relict inclusions in silicates, with average Cr, Fe, Al and Zn contents of 1.201, 1.241, 0.411 and 0.107 a.p.f.u., respectively. Amphibole, epidote, mica and chlorite show average Cr contents of 0.088, 0.138, 0.115 and 0.267 a.p.f.u., respectively, in dolomitic marbles, and 0.103, 0.078, 0.065 and 0.185 a.p.f.u., respectively, in ankeritic marbles. Cr-silicates formed through metamorphic reactions involving detrital Cr-rich spinel, in addition to clay minerals and carbonates. The B necessary to form tourmaline was probably derived from the leaching of underlying evaporitic rocks.

Lobanovite, K2Na(Fe42+Mg2Na)Ti2(Si4O12)2O2(OH)4, is a new mineral of the astrophyllite supergroup from Mt. Yukspor, the Khibiny alkaline massif, Kola Peninsula Russia. It has been known previously under the following names: monoclinic astrophyllite, magnesium astrophyllite, magnesiumastrophyllite and magnesioastrophyllite but has never been formally proposed and approved as a valid mineral species by the Commission on new Minerals, Nomenclature and Classification of the International Mineralogical Association. It has now been revalidated and named lobanovite after Dr. Konstantin V. Lobanov, a prominent Russian ore geologist who worked in the Kola Peninsula for more than forty years (Nomenclature voting proposal 15-B). Lobanovite has been described from pegmatitic cavities on Mt. Yukspor where it occurs as elongated bladed crystals, up to 0.04 mm wide and 0.2 mm long, with a straw yellow to orange colour. Associated minerals are shcherbakovite, lamprophyllite, delindeite, wadeite, umbite and kostylevite. Lobanovite is biaxial (–) with refractive indices (λ = 589 nm) α = 1.658, βcalc. = 1.687, γ = 1.710; 2Vmeas. = 81.5– 83°. Lobanovite is monoclinic, space group C2/m, a = 5.3327(2), b = 23.1535(9), c = 10.3775(4) Å, β = 99.615(1)°, V = 1263.3 (1) Å 3, Z = 2. The six strongest reflections in the powder X-ray diffraction data [d (Å), I, (hkl)] are: 3.38, 100, (003); 2.548, 90, (063); 10.1, 80, (001); 3.80, 60, (042,131); 3.079, 50, (132,062); 2.763, 90, (1̄71). The chemical composition of lobanovite was determined by electron-microprobe analysis and the empirical formula (K1.97Ba0.01)∑1.98(Na0.65Ca0.14)∑0.79 (Fe3.182+Mg2.02Na1.00Mn0.72)∑6.92(Ti1.99Nb0.06)∑2.05[(Si8.01Al0.06)∑8.07O24]O2(OH)4.03F0.19 was calculated on the basis of 30.2 (O + OH + F) anions, with H2O calculated from structure refinement, Dcalc. = 3.161 g cm–3. In the structure of lobanovite, the main structural unit is the HOH block, which consists of one close-packed O (Octahedral) and two H (Heteropolyhedral) sheets. The M(1–4) octahedra form the O sheet and the T4O12 astrophyllite ribbons and [5]-coordinated Ti-dominant D polyhedra link through common vertices to form the H sheet. The HOH blocks repeat along [001], and K and Na atoms occur at the interstitial A and B sites. The simplified and end-member formulae of lobanovite are K2Na [(Fe2+,Mn)4Mg2Na]Ti2(Si4O12)2O2(OH)4 and K2Na(Fe42+Mg2Na)Ti2(Si4O12)2O2(OH)4, respectively.