Whiteite, Ca(Fe,Mn)2+Mg2Al2(OH)2 (H2O)8[PO4]4, a 14·90(4) Å, b 6·98(2) Å, c 10·13(2) Å, β 113° 07(10)′, Z = 2, space group P2/a, α 1·580(5), β 1·585(5), γ 1·590(5), 2V 40–50°, specific gravity 2·58, is a new species from the Ilha de Taquaral, Minas Gerais, Brazil. It is the Al3+-analogue of jahnsite. The mineral occurs as up to 5 mm tan crystals flattened on {001}. Twinning by reflection on {001} leads to pseudoorthorhombic development. Rather pure material also occurs from Blow River, Yukon Territory, Canada.

For the general formula XM(1)M(2)2M(3)2(OH)2 (H2O)8[PO4]4, it is proposed that for M(3), Al3+ > Fe3+, the established members of the series are whiteite—(CaFe2+Mg) and whiteite—(Mn2+Fe2+Mg); and for Fe3+ > Al3+, jahnsite—(CaMn2+Mg), jahnsite—(CaMn2+Fe2+), and possibly jahnsite—(Mn2+Mn2+Mn2+).

Xanthoxenite of Laubmann and Steinmetz (1920) is probably stewartite (in part) on the basis of morphological, optical, physical, and paragenetic evidence. The xanthoxenite of Frondel (1949) is proposed as the species type. It is triclinic, P or P1, a 6·70(4) Å, b8·85(4) Å, c 6·54(3) Å, α 92·1(2)°, β 110·2(2)°, γ 93·2(2)°, Z = 1 for composition .

Salmonsite, c. from Pala, California, is shown to be an intimate mixture of hureaulite and jahnsite on the basis of calculated and observed powder patterns and on reinterpretation of the original chemical analysis published by Schaller (1912). It is a breakdown product resulting from oxidation of Fe2+ in the original hureaulite (‘palaite’) along with further aquation followed by fine-grained recrystallization. The reaction proposed is:

The morphology of calcium metasilicate produced during the crystallization of glasses and melts of approximately metasilicate composition has been investigated. Both isothermal heat treatments and a dynamic crystal-pulling technique were employed. The crystallization took place by a dendritic or spherulitic mechanism, according to which of the crystal polymorphs is stable under the prevailing conditions. The morphology of the crystals is controlled by the ease with which the anionic groups present in the amorphous phase can be incorporated into the growing crystals. This is reflected in the values of the activation energies of crystal growth found for α-CaSiO3 (160 kJ mol−1) and for β-CaSiO3 (319 to 383 kJ mol−1). The Keith and Padden theory of spherulitic crystallization was verified for the growth of β-CaSiO3 over a range of supercoolings. Time-temperature-transformation diagrams have been constructed from the experimental data.

Rhythmic layering in the Skaergaard intrusion shows variation in crystal size and in modal proportions of primocrysts with structural height. These changes are ascribed to variations in nucleation rates of primocrysts. The nucleation theory requires that crystallization occurs under supercooled conditions, and that the crystallization of one primocryst phase may change the composition of the magma in such a manner that the nucleation rates of other primocrysts are influenced. Both these constraints appear to have been fulfilled for the Skaergaard intrusion.

Electron-microprobe analyses of cumulus olivine, chromite, pyroxene, and plagioclase from layered peridotites and allivalites of the Eastern and Western Layered Series of Rhum demonstrate the presence of cryptic variation. Olivine varies from Fo88-78 within individual units, and there are corresponding changes in the Mg/(Mg+Fe2+) ratios in the pyroxenes and chromites. Plagioclase changes are not so dramatic, but the An-content broadly follows the Mg/(Mg+Fe2+) ratio in the other minerals. The most Fe-(and Na-) rich phases do not occur at the top of lithological units, but some way below. The composition trend above them is reversed. The data are interpreted as the result of periodic infilling of a magma chamber, the new magma mixing with the remains of the previous pulse. Each pulse was followed by a period when fractional crystallization produced the layered rocks. New data on Ni in the olivines suggests that the ratio of the volume of initial magma to volume of layered rocks was about four to one, the initial magma being allied to the high-calcium low-alkali tholeiitic basalts of Skye.

Black tourmaline from Corrego do Urucum, Brazil, is an elbaite coloured by iron and manganese with blue, green, and pink regions. Polarized spectra show the absorption bands expected in elbaite (Fe-caused blue and green, and pink, which is probably caused by Mn). The colour distribution in the transverse sections does not conform to the symmetry of tourmaline and changes along the length of the crystals. Two distinct growth stages are indicated, separated by a partial dissolution and followed by another dissolution.

Full chemical analysis, cell dimensions, γ refractive index, density, and infra-red absorption spectrum have been determined for fourteen stilpnomelanes. Coupled with data from previously described material and electron probe analyses of three further samples, the new information shows that γ = 1·616+0·0047 Fe3+ −0·0037 Mg; substitution of Mn for Fe appears to have little effect on γ. For ferrostilpnomelane, D = 2·85−0·011 Mg, for ferristilpnomelane, D = 2·89−0·011 Mg. Cell dimensions clearly distinguish ferro-, ferri-, and man-ganstilpnomelanes; for ferri-stilpnomelane a = 22·03−0·00446 Mg−0·00786 Fe3+ (Å). A convenient approximation to the structural formula using a ⅛ subcell, is K0·6(Mg, Fe2+Fe3+)6Si8Al(O,OH)27 2–4 H2O.

Sampleite from Jingemia Cave, Watheroo (30° 16′ S. 116° 00° E.), 190 km north of Perth, Western Australia is derived from the alteration of copper sulphides in contact with guano deposits. Associated minerals are atacamite, weddellite, and gypsum on goethite and manganese-oxide-coated friable quartz rock. Birnessite, halite, dolomite, taranakite, todorokite, apatite, and malachite are also present.

The sampleite occurs as platy spheroidal aggregates to 0·3 mm with D 3·20±0·01, α 1·625 ∥ [010], β and γ 1·674, all ±0·002, α Turquoise Green 41d to Light Blue-Green 39d, β and γ Benzol Green 41 to Venice Green 41b, absorption α < β = γ, 2Vα 5–10°. Chemical analyses are given.

Cu3(PO4)2·3H2O, a corrosion product reported on artifacts, is believed to be sampleite. A further occurrence of sampleite has been recorded from Brookton, 120 km ESE. of Perth. The structurally related mineral lavendulan has been reported from five Western Australian localities.

Analyses of glauconites and celadonites from continental sedimentary rocks and sea-floor basalts using X-ray diffraction, electron probe microanalysis, infra-red spectroscopy, and X-ray fluorescence spectroscopy are reported. The minerals are shown to be distinct species; each an isomorphous replacement series, glauconite having an average half unit cell of K0·85(Fe3+, Al3+)1·34 (Mg2+, Fe2+)0·66(Si3·76Al0·24)O10(OH)2 whereas celadonite approaches the ideal half unit cell of K(Fe3+, Al3+)(Mg2+, Fe2+)Si4O10(OH)2. Considerable Fe3+Alvi interchangeability occurs in the octahedral layer in both minerals and considerable substitution of aluminium in the tetrahedral layer of glauconites results in the more disordered 1Md type of structure compared with the more highly ordered 1M structure of celadonites. Some mixed layer glauconite-smectites and celadonites were also examined and could be distinguished from true glauconites and celadonites by chemical analysis, XRD, and IR techniques. It is proposed that the terms ‘glauconite’ and ‘celadonite’ should be used only for those minerals containing less than 5% interlayering.

Tacharanite in fractures in metagabbroic rocks filled by zeolitic assemblages has been found in the Gruppo di Voltri, Ligurian Alps. Optical properties, chemical analysis, and thermal data are reported, also mineralogical data on tobermorite found at another locality of the Gruppo di Voltri. Alteration of tacharanite into tobermorite and gyrolite was not observed, nor was an association of tacharanite and tobermorite.

An occurrence of the magnesian zeolite ferrierite at Unanderra, New South Wales, represents the first reported locality for this mineral in Australia. The ferrierite occurs in vesicles in latite and is associated with heulandite, laumontite, and calcite. Its crystal morphology is essentially similar to that of specimens from the type locality at Kamloops Lake in British Columbia. EPMA results are given for the Unanderra ferrierite and its chemistry relative to other known occurrences is discussed. Unanderra ferrierite contains appreciably more SrO2 than other ferrierites, but is significantly lower in K2O and Na2O.

The variation in the structural state of potassium feldspars from the St. George pluton, New Brunswick, Canada, is discussed. Monoclinic potassium feldspars occur near the eastern end of the pluton whereas the granites at the western end contain triclinic potassium feldspars. Although the bulk compositions of the host rocks are all very near the granite minimum melt composition there is a systematic increase in the degree of ordering for both the triclinic and monoclinic suites of feldspars with the more ordered variants tending to occur within rocks nearest the minimum melt composition. There is more abundant textural evidence for the presence of a late-stage fluid phase in the granites containing the monoclinic potassium feldspars. It is proposed that a slower post-crystallization cooling rate was also a factor in the nucleation of triclinic domains in the potassium feldspars at the western end of the pluton.

A new mineral, sasaite, occurs as white chalky nodules in the soil of a dolomitic cave and seems to be derived from the action of bat guano on clay minerals. Under the microscope it consists of an agglomeration of plates 10–20 µm on greatest dimension and with a rhombic shape. Its formula is (Al, Fe3+)14(PO411(OH)7SO4·83H2O and it is orthorhombic or quasi-orthorhombic. Preliminary crystallographic data based on an orthorhombic cell are a 21·50, b 30·04, c 92·06 Å, Z10, based on a calculated density of 1·747 (observed 1·75). The optical indices are α 1·465, β 1·473, γ 1·477 all ±0·001, and the principal vibration directions are parallel or quasi-parallel to the crystallographic axis.

A suite of unusual acicular hornblende schists is found at Warsak (34° 10′ N. 71°C 23′ E.), some 30 km WNW. of Peshawar, North-West Pakistan. The schists occur in association with sill-like masses of amphibolite facies meta-igneous rocks, possibly a metamorphosed gabbroic and doleritic, dioritic, and granitic calc-alkaline series, and intrusions of alkaline granite and microgranite. These rocks lie within Palaeozoic metasediments and all are folded synclinally. The area was first described by Ahmad et al. (1969).

The rocks of the acicular hornblende schist suite (fig. I) consist essentially of large, idioblastic hornblende crystals—comprising some 30–60 % of the rock—in a fine-grained granoblastic matrix of oligoclase feldspar with minor quartz, iron oxide, biotite, and rutile. The boat-shaped, blue-green hornblendes, twinned on {100}, reach 5 mm in length and are often grouped in sprays or clusters; they are sieved with quartz, ilmenite, and patchy calcite. The groundmass also contains patches and veins of calcite, associated with ragged patchy areas of reddish brown, amorphous iron oxide or hydroxide, perhaps introduced hydrothermally. The schists coarsen in grain size outwards through the sill-form, the hornblendes reaching 4 cm, become rich in chlorite and biotite, and grade into the apparently metagabbroic amphibolitic rocks.

The acicular hornblende schists have a generally basaltic composition, while the hornblendes are tschermakitic. An analysed amphibole has 16·5% Al2O3, is slightly zoned with alumina increasing from core to rim, and has the formula:

Three hypotheses of the origin of the rocks were considered; metamorphism of a suite of basic tufts is the most favoured. Origins involving metamorphism of a lamprophyre-appinite suite or of a gabbroic marginal facies are therefore rejected. Texturally the rocks strongly resemble metatuffs (fig. 2) that occur associated with metagreywackes in the Otago schists of New Zealand (Turner, 1933); like many similar Alpine schists they also contain tschermakitic hornblendes. The Warsak tufts could have formed originally, together with the meta-igneous rocks, possibly as lavas, in an inter-plate tectonic environment; the high A1 content of the hornblende, which is typical of many amphiboles from the surrounding alpine environment in North-West Pakistan, and other mineralogical evidence in the region support a highpressure environment for the metamorphism of the rocks to just within the amphibolite facies, at moderate temperatures of approximately 465 °C.

The Kondapalli region (16° 37′ N. 80° 32′ E.) in the Eastern Ghats, Andhra Pradesh, consists of high-grade granulite facies rocks: charnockites, hypersthene granites, and enderbites are plutonic intrusives into khondalites—garnetiferous sillimanite granites, garnetiferous granites, siltimanite-garnet quartzites, and quartzites. Pyroxene granulites of gabbroic and noritic compositions are distinct basic intrusive bodies, occurring as sills and dykes.

Chromite orthopyroxene nodules are enclosed in serpentinite and carbonate rock, formed from altered peridotite; they are younger than the charnockites and pyroxene granulites and are confined to the cores of south-eastern-plunging overturned isoclinal anticlines. The chromites are massive in coarse-layered pyroxenites and granular in fine-layered rocks; those found at Gangineni are magnetic and are associated with bronzite (En77–85), those from the Binny and Loya mines are non-magnetic and associated with enstatite (En88–95).

Chemical analyses and X-ray powder data are given for five specimens, including both types. The magnetic susceptibility appears to increase with increasing Fe3+. The unit-cell size is negatively correlated with Cr3+, A13+, and Mg2+ and positively with Fe2+ and Fe3+.