Among the specimens collected at the Benallt manganese mine in 1944 by Dr. A. W. Groves and myself was one (B.M. 1944,48) from the 60-foot level in no. 1 ore-body which showed on a face of dark, compact manganese ore colourless plates up to 7 mm. across and about ½ mm. thick. These plates proved to be uniaxial and negative with perfect basal cleavage. Heated in an ignition tube the fragments decrepirated, gave off water, and became pearly, white, and opaque. Qualitative tests showed Ba, Al, and SiO2 to be present. Preliminary X-ray photographs revealed hexagonal symmetry, but could not be matched with those of any known mineral.

This paper concludes the account of our experiments on halloysite and is to be read in conjunction with the two previous parts, to which frequent reference will be made.

The effect of heat-treatment on metahalloysite was examined with the primary object of ascertaining if a recrystallization or ‘kaolinization’ of metahalloysite could be achieved.

Samples of magnetite containing exsolution bodies of ilmenite, or of ulvöspinel and ilmenite, were heated at 1,250–1,300° C. under oxidizing and under reducing conditions.

In the former case, the product consisted of magnetite, ferri-ilmenite, and pseudobrookite. In the latter, loss of oxygen converted a magnetite-ilmenite intergrowth into a homogeneous Fe3O4-Fe2TiO4 spinel solid solution, while a magnetite sample originally carrying ulvöspinel in addition to ilmenite yielded a spinel phase with surprisingly low cell dimension, together with some metallic iron.

The new REE-rich, monoclinic, epidote-supergroup minerals ferriakasakaite-(La) and ferriandrosite-(La), found in tephroite calcite veinlets cutting the stratiform ferromanganese deposit from the Shobu area, Ise City, Mie Prefecture, Japan, were studied using electron microprobe analysis and single-crystal X-ray diffraction methods. Ferriakasakaite-(La), ideally A1CaA2LaM1Fe3+M2AlM3Mn2+(SiO4)(Si2O7)O(OH) (Z = 2, space group P21/m), has a new combination of dominant cations at A1(Ca) and M3(Mn2+), which are the key sites to determine a root name for epidote-supergroup minerals. The unit-cell parameters are a = 8.8733(2), b = 5.7415(1), c = 10.0805(3) Å, β = 113.845(2)° and V = 469.73(2) Å3. According to the structural refinement (R1 = 3.13%), the determined structural formula is A1(Ca0.54Mn2+0.46)A2[(La0.48Ce0.20Pr0.07Nd0.18Gd0.02)Σ0.95Ca0.05]M1(Fe0.423+V0.343+Al0.18Ti0.064+)M2(Al0.96Fe0.043+)M3(Mn0.502+Fe0.432+Mg0.07)(SiO4)(Si2O7)O(OH). Ferriandrosite-(La), ideally A1Mn2+A2LaM1Fe3+M2AlM3Mn2+(SiO4)(Si2O7)O(OH) (Z = 2, space group P21/m), is the M1Fe3+ analogue of androsite. The unit-cell parameters are a = 8.8779(1), b = 5.73995(1), c = 10.0875(2) Å, β = 113.899(1)° and V = 469.97(2) Å3, and the structural formula is A1(Mn0.562+Ca0.44)A2[(La0.49Ce0.20Pr0.08Nd0.19Gd0.02)Σ0.97Ca0.03]M1(Fe0.403+V0.283+Al0.20Fe0.052+Ti0.074+)M2(Al0.97Fe0.033+)M3(Mn0.502+Fe0.402+Mg0.10)(SiO4)(Si2O7)O(OH) (R1 = 2.93%). The two new minerals, which are compositionally very similar overall, are distinguished by occupancy of A1, Ca vs. Mn2+. The structural properties of these minerals depend not only on the REE content at A2, but also on the Mn content at A1.

Earthworms are an essential part of the soil fauna in many global soils, represent a significant proportion of the soil biomass and are regarded as a useful indicator of soil health and quality (Edwards, 2004). They are also often the subject of inoculation programmes during the restoration of degraded lands (Butt, 1999) and the inoculation of earthworms to metal-contaminated soils has been suggested(Dickinson, 2000) largely due to the role earthworms are known to play in soil formation at such sites (Frouz et al., 2007).

Chemical analyses and physical properties are given for six samples of beryl from greisenized granites, pegmatites, and beryl-quartz veins in the Rosses granite complex. The beryls studied were all very similar in composition and contain significant amounts of alkali elements and water in addition to the constituents represented by the formula Be3Al2Si6O18. Calculation of the empirical unit cell contents indicates that most of the H2O+ is present in the mineral as water molecules. The effects of these extra constituents on the physical properties are discussed, and it is suggested that the variation in refractive indices displayed by beryl is to a large extent attributable to the variable water content.

Kerimasite {Ca3}[Zr2](SiFe23+)O12, a rare member of the garnet supergroup, has been identified in association with andradite–grossular and their hydrated analogues, monticellite, perovskite, clintonite, anhydrite, hydroxylellestadite–fluorellestadite, spinel, magnetite, brucite, valeriite and other minerals from a Ca-Mg skarn in the exocontact of a granodiorite porphyry intrusion in Vysoká-Zlatno Cu-Au skarn-porphyry deposit, the Štiavnica stratovolcano, Central Slovakia. Kerimasite forms euhedral-to-anhedral crystals, 2 to 100 μm across with 0.73–1.62 atoms per formula unit (a.p.f.u.) Zr (16.2–33.6 wt.% ZrO2), 0.34–0.66 a.p.f.u. Ti (4.6–9.3 wt.% TiO2), 0.01 to 0.05 a.p.f.u. Hf (0.4–1.7 wt.% HfO2: the largest Hf content reported in kerimasite), and small amounts of Sn, Sc and Nb (≤0.02 a.p.f.u.). Tetrahedral Si (0.99–1.67 a.p.f.u.; 9.8–18.1 wt.% SiO2) is balanced by 0.85–1.26 a.p.f.u. Fe3+ and by 0.46–0.76 a.p.f.u. Al. The crystals commonly show regular, oscillatory concentric zoning or irregular patchy internal textures due to Zr, Ti, Fe, Al and Si variations during growth or partial alteration and dissolution-reprecipitation. The main substitutions in kerimasite are Y(Fe,Sc)3+ + ZSi4+ = Y(Zr,Ti,Hf,Sn)4+ + Z(Fe,Al)3+ and Ti4+ = Zr4+. Associated andradite locally contains irregular Ti- and Zr-rich zones with ≤11 wt.% TiO2 and ≤4.4 wt.% ZrO2. In comparison with common Ca-rich garnets, the micro-Raman spectrum of kerimasite shows that many bands shift towards much lower wavenumbers, either due to Fe3+ substitution on the Z site or to the strong influence of neighbouring octahedrally-coordinated Zr4+ on internal vibrations of tetrahedra that share oxygens. The formation of kerimasite, monticellite, perovskite and other phases indicate a relatively Ca-rich and Si, Al-poor environment, analogous to other known occurrences of Ca-Zr garnets (Ca-rich skarns and xenoliths, carbonatites). Kerimasite and associated skarn minerals originated during contact-thermal metamorphism of Upper Triassic marl slates with limestone, dolomite, anhydrite and gypsum by Miocene granodiorite porphyry at T ≈ 700°C and P ≈ 50–70 MPa.

Chemical analyses and structural formulae of biotites from the Zaër pluton, a zoned granitic body in the Central Hercynian Massif of Morocco, are presented. The pluton grades from more mafic single-mica granodioritic facies near the margin to more felsic two-mica granitic facies in the central part. There is a relationship between the composition of the biotites and that of the host rocks. Biotite composition in the internal two-mica facies was influenced by a hydrothermal phase.

Jentschite, TlPbAs2SbS6, is a new sulphosalt mineral from the famous Lengenbach locality (Binntal, Switzerland). It was discovered in association with numerous other Tl-As-sulphosalts such as hutchinsonite, wallisite-hatchite, edenharterite, bernardite, abundant realgar and orpiment in small cavities in a dolomitic rock of Triassic age which forms part of the Penninic Monte-Leone-nappe. The first specimens consisted of extremely small polysynthetically twinned crystals; a later find yielded less complicated twinned crystals in sizes up to 2 mm length. Single crystal X-ray diffraction studies gave a monoclinic cell with a = 8.121(3), b = 23.969(9), c = 5.847(3) Å, β = 107.68(3)° V = 1084.3(5) Å3, Z = 4, space group P21/n. The strongest lines in the X-ray powder diagram are (dobs in Å, Iobs, hkl): 2.823 (100)(116), 3.587 (86)(221), 2.778 (84)(260), 3.998 (74)(060), 2.670 (58)(301), 3.816 (54)(210). Chemical composition (electron microprobe, mean of 15 analyses, wt.%) is: Tl 23.92, Pb 21.44, As 19.16, Sb 12.53, S 22.42, total 99.47 wt.% from which a simplified formula TlPbAs2Sb1S6 can be derived. This formula is very close to that of the (orthorhombic) mineral edenharterite TlPbAs3S6. From structural and chemical data it was interpreted as the ordered structure of an Sb-bearing relative of edenharterite, a postulation that meanwhile could be confirmed by the complete structure determinations of both, edenharterite and jentschite (Berlepsch, 1996). Jentschite occurs in prismatic crystals up to 2 mm length; it is opaque with a black metallic to submetallic luster, red translucent in thin fragments. Fracture is uneven to conchoidal, the mineral is extremely brittle, the cleavage along (01) is perfect; the streak is dark red (darker than that of edenharterite). Mohs hardness is 2–2½, according to a microhardness VHN (10 g load) of 38–51 kg/mm2. The calculated density yields Dcalc = 5.24 g/cm3.

The name is for Franz Jentsch (1868–1908) from Binn, a local ‘Strahler’ and for several years head of an early Lengenbach syndicate that exploited the rare Lengenbach sulphosalt minerals at the beginning of this century.

Pisolitic ironstones occur at various localities in North Wales, at about the horizon of Nemagraptus gracilis. The rocks have undergone considerable folding and the hard ironstones are often faulted and in many cases deformed. Greenstone dikes frequently intersect the beds, usually with little visible alteration of the ore, though the ironstones are generally hardened, with incipient re-crystallization of the chamosite. At Pen-y-rallt iron mine, situated half a mile east of Llanfrothen church near Penrhyndreudraeth in Merionethshire, a steeply inclined pisolitic ironstone bed rests upon a mass of igneous rock; and here the alteration of the ore is in a more advanced stage, for the ironstone is in places seamed with roughly parallel asbestiform veins (up to 1 inch) which contain a brittle dark-brown mineral strongly resembling biotite ; the centre of the vein is sometimes filled with chalybite.

The formation of columbite has been observed in two carbonatites in south-west Tanganyika where it is due to autometasomatism following the emplacement of the bodies. Disoriented aggregates of columbite crystallites are formed as pseudomorphs after eubo-octahedra of pyrochlore in sövite. This alteration is accompanied by the addition of Fe, conversion of amphibole and biotite in the sövite to a ferruginous tale. the formation of an iron-bearing carbonate, and the introduction of colloform silica: Ca and Na are lost in part. The general alteration of the sövite can be ascribed to the influx of iron-bearing solutions at relatively low temperature and high pressure.

The sedimentary iron ores of Britain all contain small amounts of phosphorus which is generally present in the colloform mineral collophane. In a rather uncommon class of oolitic ironstones recently described from the Yorkshire coalfield, a crystalline phosphate was found which has now been identified as francolite and forms the subject of this paper. These oolitic ironstones occur in the immediate roofs of coal seams, are of freshwater origin, and consist of ooliths of kaolinite and isotropic clay in a groundmass of chalybite. During the later stages of their diagenesis, francolite, associated with quartz, calcite, pyrite and blonde, and much kaolinite, crystallized within the ooliths (fig. 1) and in the shrinkage cracks (fig. 2) of the ironstone, and sometimes replaced the ooliths and groundmass. The francolite is present in all of the three oolitic ironstone occurrences described from Yorkshire, and also in the similar rock from Derbyshire in the Geological Survey's collection of iron ores. Details of these localities are given in the ironstones paper. The writer has also found similar francolite in an ironstone nodule from a parting in the Mühlenbach coal seam of south Limburg, Netherlands. Although not recorded, it may be expected to occur in some of the black-band ironstones and other rocks closely associated with coal seams. The following account is based entirely on material from Robin Hood quarry, Thorpe-on-the-Hill, 4 miles south of Leeds.

Bettertonite, ideally [Al6(AsO4)3(OH)9(H2O)5]·11H2O, is a new mineral from the Penberthy Croft mine, St. Hilary, Cornwall, England, UK. It occurs as tufts of white, ultrathin (sub-micrometre) rectangular laths, with lateral dimensions generally <20 μm. The laths are flattened on {010} and exhibit the forms {010}, {100} and {001}. The mineral is associated closely with arsenopyrite, chamosite, liskeardite, pharmacoalumite, pharmacosiderite and quartz. Bettertonite is translucent with a white streak and a vitreous to pearly, somewhat silky lustre. The calculated density is 2.02 g/cm3. Optically, bettertonite is biaxial positive with α = 1.511(1), β = 1.517(1), γ = 1.523(1) (in white light). The optical orientation is X = c, Y= b, Z = a. Pleochroism was not observed. Electron microprobe analyses (average of 4) with H2O calculated on structural grounds and analyses normalized to 100% gave Al2O3 = 29.5, Fe2O3 = 2.0, As2O5= 30.1, SO3 = 1.8, Cl = 0.5, H2O = 36.2. The empirical formula, based on 9 metal atoms is Al5.86Fe0.26(AsO4)2.65(SO4)0.23(OH)9.82Cl0.13(H2O)15.5. Bettertoniteis monoclinic, space group P21/c with unit-cell dimensions (100 K): a = 7.773(2), b = 26.991(5), c = 15.867(3) Å, β = 94.22(3)°. The strongest lines in the powder X-ray diffraction pattern are [dobs in Å(I)(hkl)] 13.648(100)(011); 13.505(50) (020); 7.805(50)(031); 7.461(30)(110); 5.880(20)(130); 3.589(20)(02); 2.857(14)(182). The structure of bettertonite was solved and refined to R1 = 0.083 for 2164 observed (I > 2σ(I)) reflections to a resolutionof 1 Å. Bettertonite has a heteropolyhedral layer structure, with the layers parallel to (010). The layers are strongly undulating and their stacking produces large channels along [100] that are filled with water molecules. The basic building block in the layers is a hexagonal ring ofedge-shared octahedra with an AsO4 tetrahedron attached to one side of the ring by corner-sharing. These polyoxometalate clusters, of composition [AsAl6O11(OH)9(H2O)5]8–, are interconnected along [100] and [001]by corner-sharing with other AsO4 tetrahedra.

The Zhenzhu Spring, located in the Tengchong volcanic field, Yunnan, China, is an acid hot spring with high SO42− concentrations and intense acid aerosol generation. In order to understand the formation mechanism of sulfate minerals at the Zhenzhu Spring and provide a better insight into the sulfur isotope geochemistry of the associated Rehai hydrothermal system, we investigated the spring water hydrochemistry, mineralogy and major-element geochemistry of sulfate minerals at the Zhenzhu Spring together with the sulfur-oxygen isotope geochemistry of sulfur-containing materials at the Rehai geothermal field and compared the isotope results with those in other steam-heated environments. Subaerial minerals include a wide variety of sulfate minerals (gypsum, alunogen, pickeringite, tamarugite, magnesiovoltaite and a minor Mg–S–O phase) and amorphous SiO2. The δ34S values of the subaerial sulfate minerals at the Zhenzhu Spring varied subtly from –0.33 to 1.88‰ and were almost consistent with the δ34S values of local H2S (–2.6 to 0.6‰) and dissolved SO42− (–0.2 to 5.8‰), while the δ18O values (–8.94 to 20.1‰) were between that of the spring waters (–10.19 to –6.7‰) and atmospheric O2 (~23.88‰). The results suggest that most of the sulfate minerals are derived from the oxidation of H2S, similar to many sulfate minerals from modern steam-heated environments. However, the rapid environmental change (different ratio of atmospheric and water oxygen) at the Zhenzhu Spring accounts for the large variation of δ18O. The formation of subaerial sulfate minerals around the Zhenzhu Spring is related to acid aerosols (vapour and acid water droplets). The intense activity of spring water around vents supply the aerosol with H2SO4 (H2S oxidation and acid water droplets formed by bubble bursting) and few cations. Deposition of the acid sulfate aerosol forms the acid condensate, which attacks the underlying rocks and releases many cations and anions to form subaerial sulfate minerals at the Zhenzhu Spring.

Lead-bearing phyllotungstite from the Clara mine in the central Black Forest, Germany has a formula (Cs0.41)Na0.14K0.05Pb2+2.01Ca0.26[W6+10.87Fe3+3.13O35.75(OH)6.25](O(H2O)3). X-ray diffraction patterns exhibit pseudohexagonal symmetry, but refinement of single-crystal synchrotron data has shown that the true symmetry is orthorhombic, Cmcm, with a = 7.298(1), b = 12.640(2), c = 19.582(4) Å, and that the pseudohexagonal character is due to submicrometre-scale cyclical twinning by rotation about the pseudohexagonal c axis. The structure can be described in terms of an ordered intergrowth, parallel to (001), of (111)py blocks with pyrochlore-type structures, which are ~6 Å in width, and two-layer wide regions with a hexagonal tungsten bronze (HTB) type structure. Caesium atoms occupy 18-coordinate cavities in the HTB regions, and H2O molecules occupy Φ sites in the A2B2O6Φ pyrochlore blocks. The lowering of symmetry from hexagonal to orthorhombic is due to partial ordering of W and Fe in the octahedral B sites and of Pb and vacancies in the A sites of the pyrochlore blocks. The ideal formula for the intergrowth structure (with no vacancies) is C 2A10[B14(O,OH)42]Φ4, where C is the cavity site in the HTB slabs. The mineral has only 21% occupancy of the C site and 25% occupancy of the A site, but full occupancy of the Φ site. There may be some mixing of Cs and H2O between the C and Φ sites.

Xenotime-(Y), (Y,REE)PO4, and thortveitite, (Sc, Y)2Si2O7, in a miarolitic cavity in a niobium, yttrium, fluorine (NYF) granitic pegmatite at Baveno, Verbania, Southern Alps, Italy, were investigated by electron microprobe analysis and single-crystal X-ray diffraction. Fluorine has an important role as a complexing agent for Y and REEs in supercritical pegmatitic fluids; annitesiderophyllite and chamosite are the most likely sources of the Y and REEs. The thortveitite from Baveno contains up to 3.20 wt.% SnO2, an unusually high Sn content. Xenotime-(Y) is enriched in Gd in comparison to other Alpine xenotimes. Quantitative chemical data and measurements of the lattice parameters show that a higher scandium content results in a smaller unit-cell volume in thortveitite. The substitution of REEs for Y up to ∼20 mol.% has little effect on the unit cell of xenotime-(Y). The textures of xenotime-(Y) and thortveitite provide information about the dissolution and crystallization processes in the miarolitic cavity.