Data for U, Th, and K, determined by neutron activation analysis, in 128 rock samples from 14 Irish Caledonian and Tertiary granite plutons are sum-marized. Irish Newer Caledonian granites (ninety-four samples) have values of radioelements (average 3.6 ppm U, 12.1 ppm Th, and 3.4% K) consistent with derivation from a source of broadly uniform composition. U mineralization occurs in the voluminous and forcefully emplaced Main Donegal and Leinster plutons whereas smaller passively emplaced granites (Galway, Barnesmore, Rosses) lack mineralization. Irish Tertiary granites (thirty-four samples), which represent small batches of highly fractionated acid magmas, show moderate or high radioelement contents (11.5 ppm U, 39.9 ppm Th, 4.5% K) but are not mineralized. It is concluded that the use of elevated radioelement contents as a criterion of granite ‘fertility’ may be misleading in the British Isles Caledonian Province. The radioelement chemistry of granites may reflect their source composition more closely than expected for differentiated and/or contaminated acid melts.

Paratooite-(La) is a new lanthanum-dominant rare-earth copper carbonate from the Paratoo copper mine, near Yunta, Olary district, South Australia. Paratooite-(La) occurs as sheaves and radiating sprays of blade-like to tabular pale blue crystals in thin fissures in a slaty country rock. Individual crystals are typically 50–200 μm in maximum dimension but <5 μm thick. Associated minerals include donnayite-(Y), kamphaugite-(Y), and bastnäsite-(La). Electron microprobe and CHN analyses gave: La2O3 26.47; Pr2O3 7.74; Nd2O3 8.15; Sm2O3 0.66; Gd2O3 0.85; Y2O3 0.72; CaO 7.57; SrO 3.15; Na2O 3.3; CuO 5.77; F 0.24; CO2 32.05; NO2 1.12; -O=F -0.10; sum 100.03, yielding an empirical formula of (La3.54Ca2.94Na2.32Nd1.05Pr1.03Sr0.66Y0.14Gd0.10Sm0.08)Σ11.86Cu1.58(C15.84N0.53)O47.76F0.24. The simplified formula is (REE ,Ca,Na,Sr)6Cu(CO3)8 or possibly REE3(Ca,Sr)2NaCu(CO3)8. The mineral is pale turquoise-blue to pale blue in colour, transparent, with a pearly to vitreous lustre and a pale blue streak. No cleavage was observed but the morphology and TEM studies indicate a cleavage parallel to ﹛100﹜. The Mohs hardness is estimated to be 4. The strongest lines in the X-ray powder pattern are [dobs (Iobs) (hkl )]: 5.047 (53) (200); 4.786 (49) (021); 3.957 (43) (220); 3.468 (43) (012, 221); 2.927 (100) (202); 2.530 (52) (241); 2.344 (22) (420,103); 2.232 (20) (421). A synchrotron powder diffraction pattern was indexed on a primitive orthorhombic cell with a = 10.0862(5), b = 12.8088(6), c = 7.2360(4) Å, V= 934.8(1) Å3 and Z = 2. The crystal structure of the new mineral could not be determined but powder diffraction data indicate the space group is probably P 222, Pmmm , P 2221 or Pmm2. The measured density is 3.68(3) g/cm3 and the calculated density is 3.78 g/cm3. Paratooite-(La) is biaxial negative with α = 1.605(3), β = 1.696(3) and γ = 1.752(2); pleochroism is medium strong; X very pale bluish, Y and Z bluish (with greenish tint) with absorption Z ≈ Y >> X. Paratooite-(La) is a supergene mineral which precipitated from mildly basic carbonated groundwaters. The mineral is named for the type locality.

The crystal structure of argentobaumhauerite is reported for the first time from a sulfosalt aggregate from Lengenbach deposit, Binntal, Switzerland. The chemical formula of argentobaumhauerite, calculated in agreement with the results of structure determination is Cu0.06Ag1.20Tl0.18Pb21.46Sb0.56As32.28 S72.26. The difference from the idealized baumahuerite formula, Pb12As16S36, and from the formula of Ag – , Tl- and Sb-free baumhauerite from Moosegg, Austria, Pb11.80As16.28S35.92, expresses the Ag + As and Tl + As substitution for 2Pb. Argentobaumhauerite is triclinic, a = 7.9053(10), b = 8.4680(10), c = 44.4102(53) Å, α = 84.614(2), β = 86.469(2), γ = 89.810(2)°. V(cell) = 2954.16 Å3, space group P1. Baumhauerite Pb11.80As16.28S35.92 from Moosegg is triclinic, a = 7.884(4), b = 8.345(4), c = 22.811(11) Å, α = 90.069(8), β = 97.255(8), γ = 90.082(8)°, V(cell) = 1488.8(13) Å3, space group P1. Both minerals represent the N 1,2 = 3;4 = 3.5 member of the sartorite homologous series, with As-rich slabs separated by zigzag layers of trigonal coordination prisms of lead. In argentobaumhauerite the sequence of alternating N = 3 and N = 4 slabs of baumhauerite is further modified by alternation of two distinct types of N = 4 slabs, those with Pb present in the slab interior and those with the interior Pb substituted by Ag + As. The length and arrangement of crankshaft chains of short As–S bonds differs between different slabs, and especially between the N = 4 slabs of baumhauerite and argentobaumhauerite. The name 'argentobaumhauerite' replaces the preliminary name 'baumhauerite-2a' (IMA-CNMNC; accepted proposal 15-F).

The new mineral markeyite (IMA2016-090), Ca9(UO2)4(CO3)13·28H2O, was found in the Markey mine, San Juan County, Utah, USA, where it occurs as a secondary phase on asphaltum in association with calcite, gypsum and natrozippeite. The mineral is pale yellowish-green with white streak and fluoresces bright bluish white under a 405 nm laser. Crystals are transparent and have vitreous to pearly lustre. It is brittle, with Mohs hardness 1½ to 2, irregular fracture and three cleavages: perfect on {001}; good on {100} and {010}. The measured density is 2.68 g cm–3. Crystals are blades, flattened on {001} and elongate on [010], exhibiting the forms {100}, {010}, {001}, {110}, {101}, {011} and {111}. Markeyite is optically biaxial (–) with α = 1.538(2), β = 1.542(2) and γ = 1.545(2) (white light); the measured 2V is 81(2)°; the dispersion is r < v (weak); the optical orientation is X = c, Y = b, Z = a; and pleochroism is X = light greenish yellow, Y and Z = light yellow (X > Y ≈ Z). Electron microprobe analyses (energy-dispersive spectroscopy mode) yielded CaO 18.60, UO3 42.90, CO2 21.30 (calc.) and H2O 18.78 (calc.), total 101.58 wt.% and the empirical formula Ca8.91(U1.01O2)4(CO3)13·28H2O. The six strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 10.12(69)(001), 6.41(91)(220,121), 5.43(100)(221), 5.07(33)(301,002,131), 4.104(37)(401,141) and 3.984(34)(222). Markeyite is orthorhombic, Pmmn, a = 17.9688(13), b = 18.4705(6), c = 10.1136(4) Å, V = 3356.6(3) Å3 and Z = 2. The structure of markeyite (R1 = 0.0435 for 3427 Fo > 4σF) contains uranyl tricarbonate clusters (UTC) that are linked by Ca–O polyhedra forming thick corrugated heteropolyhedral layers. Included within the layers is an additional disordered CO3 group linking the Ca–O polyhedra. The layers are linked to one another and to interlayer H2O groups only via hydrogen bonds. The structure bears some similarities to that of liebigite.

A platina sample brought to Spain in the last quarter of the 18th century is nowadays exhibited at the National Museum of Natural Sciences in Madrid. It originated from the ancient Mineralogical Museum of the School of Applied Chemistry at El Turco Street in Madrid and most probably corresponds to the material used by François Chabaneau for his experiments to purify platinum metal in the late 18th century. The sample is a heavy-mineral concentrate consisting of Pt–Fe alloys and gold nuggets associated with ilmenite–hematite, chromian spinel, goethite and minor quartz, sphene, rutile, magnetite, hornblende, garnet, calcite, pyrite, native bismuth and bismite. The Pt–Fe alloys exhibit a characteristic composition (81.97–90.75 wt.% Pt and 5.08–10.81 wt.% Fe with minor amounts of Cu, Os, Ir, Ru, Rh and Pd) and mineralogy of solid inclusions (abundant inclusions of Ir alloy as well as Os alloy, laurite–erlichmanite, bowieite, tulameenite and undetermined Pt–Pd–Ir–Rh antimonides and tellurides) that are very similar to those Pt–Fe alloys currently mined in western Colombia (the Chocó Department). These features allow us to discuss the provenance of the sample (probably from the proximal or medial reaches of any of the Chocó rivers) and evaluate the suitability of the Chabaneau's method for purifying platina. Our results show that the method became effective only with platina samples depleted or lacking iridium.

Among a number of specimens which the senior author (J. l)rugman) obtained some years ago from the widow of a mine manager, Mr. Legrand, of Belgian nationality, was one of massive blendc from the Flor de Peña mine, Lampazos, Nuevo Leon, Mexico, which carried a small quantity of a bright yellow, transparent substance that could not be identified with any known mineral. Goniometric and optical examination showed it to be monoclinic, but the material was mainly massive radiating-prismatic, and the few freely developed crystals gave only very approximate measurements (see table II). A chemical analysis by the iunior author showed it to be indeed a new mineral, a basic zinc arsenate, and the name ‘legrandite’ is proposed for it in recognition of the collector. The larger part of what remains after investigation of the small specimen has been presented to the British Museum for preservation in the mineral collection.

An elongated boss of alkali dolerite is described having a NW. trend and measuring 800 m. by 250 m. Two main rock-types occur, an ophitic feldsparrich analeime-olivine-dolerite or leucodolerite and a tesehenite with subhedral pyroxene. The second type is intrusive into the first but the two are associated in vertical veins. Both show local banding and analcime-nepheline-syenite forms a differentiate of both. Finer grained olivine-rich dolerite resembling the crinanites of Jura occurs at the NW. extremity of the boss and probably represents the original magma. All four types have been analysed and are thought to be the products of normal crystal fractionation with slight absolute iron enrichment. The boss was apparently headed not far above the existing exposures and is considered to be of Tertiary age. The pyroxene and olivine of the leucodolerite have been separated and analysed.

Previous X-ray observations by J. Lima-de-Faria and P. Gay on the transformation goethite-hematite indicate that in the process of state change at low temperatures, maxima of scattered X-ray intensity occur as satellites to strong and diffuse Bragg maxima due to hematite. These maxima define a repeat distance of about 32 Å. Corresponding satellite maxima have been observed using electron diffraction technique and satellite maxima flanking the direct beam (000) have been used to obtain a direct electron optical image of the disordered state at high magnification. Such photographs show a mainly regular fringe system with spacing of approximately 30 Å. Dislocation patterns were also observed.

The mineral tilleyite was first discovered by Larsen and Dunham in thermally metamorphosed limestones from the contact zone at Crestmore, California. It is associated there with merwinite, wollastonite, spurrite, and gehlenite, and the rock is traversed by streaks of idocrase with grossular. The amount of tilleyite in these rocks was apparently small, but in certain thermally metamorphosed limestones from Carlingford it is abundant and some specimens are practically pure tilleyite-rocks, it has been possible, therefore, to make a more detailed optical and chemical examination of this mineral. The tilleyite occurs as subidioblastic crystals when abundant, or as rounded grains in calcite-rich rocks, or as irregular plates.

The material on which the following description is based was presented by Dr. A. L. Hall to the Department of Mineralogy at Cambridge, and I am greatly indebted to him and to Prof. A. Hutchinson for affording me the opportunity of describing it. The first account of the occurrence was given by Dr. Hall, recording from Aarkop, Magoloring, 'a beautiful delicately rose-coloured mica … in compact dark bluish-grey ore as thick, short, colmnnar aggregates not unlike little books of mica with pseudo-hexagonal outlines and showing the characteristic perfect basal cleavage … the mate: rial was found on the higher slopes defining the west side of Martha's Kloof'. This description was amplified somewhat in a later publication, with the addition of an analysis (see below). As noted therein the mineral also resembles that described by Chudoba as a manganophyllite allied to the phlogopite group, but the fuller description given below reveals important differences.

Les chlorites peuvent être définis d'après G. Tschermak (I), puis t A. Lacroix (2), comme des silicates hydratés d' Al, de Mg, et de Fe, de couleur généralement verte, possédant un elivage facile suivant (001), les lames de clivages étant flexibles, sans être élastiques, comme celles du mica. Dans un travail antérieur, l'un de nous (3) avait tenté d'établir une classification de ces minéraux, en se basant directement sat les données de l'analyse chimique, sans faire intervenir d'idée théorique sur leur constitution, comme l'avait fait G. Tschermak et d'autres auteurs aprés lui. Peu de temps après, un certain nombre de recherches, effectuées à l'aide de rayons X, ont permis d'élucider les caractéres essentiels de la structure de ces phyllites. On peut done raisonnablement en tenter une nouvelle classification chimique tenant compte du schéma structural établi actuellement. C'cst ce que nous nous proposons de faire dans ce mémoire, aprés avoir exposé quelques remarques sur des travaux récents.

Reflectivities of a series of oriented polished sections through a single crystal of pyrrhotine (Fe1−αS) from Trepča, Yugoslavia, were measured by means of a spectral photometer attached to a microscope. This pyrrhotine consists of two phases, namely intermediate pyrrhotine (∼ Fe9S10) and monoclinic pyrrhotine (∼ Fe7S8), which were probably formed by exsolution. The phase relations of pyrrhotine at low temperatures are discussed. Optical data are given for the intermediate pyrrhotine from 440 to 660 mµ. From the reflectivities measured in air and oil against a carborundum standard, values of n, k, and κ were calculated for ω and ε and represented in dispersion curves. Also, sections through the various ‘indicating surfaces’ at 546 mµ are shown. The accuracy of the values, which should be approximately the same for other pyrrhotine phases, is discussed.

From the extinction curve of a biaxial crystal mounted on a spindle stage (or one-axis stage goniometer), the related n0 curve can be derived and drawn on the stereogram. The n0 curve is the equivibration curve—or constant-refractive-index curve—that goes through the projection P0 of the spindle-stage axis. After the principal diameters (maximum 2η and minimum 2ζ) of the no curve have been measured, the angle 2V may be calculated by means of the formula cos V = sin ζ/sin η. This method can also be used for determining—or refining—the directions of the principal axes α, β, γ.

The Caledonian fold belt of East Greenland contains calc-alkaline granite (sensu lato) intrusions with ages ranging from c.2000 Ma to c.350 Ma. The Proterozoic granites have low U contents and the pre-Devonian Caledonian granites contents of U corresponding to the clarke value for U in granites. Some aspects of the geochemistry of U are discussed using U-K/Rb, U-Sr, U-Zr, and U-Th diagrams. Secondary enrichment and mineralization occurs in fractured and hydrothermally altered granites and rhyolites situated in or near a major NNE fault zone. The U is associated with iron oxides or hydrocarbons. It is suggested that the source of the mineralization was Devonian acid magma, which also acted as a heat source for circulating hydrothermal fluids.

Junitoite, CaZn2Si2O7·H2O, is orthorhombic, space group Area2, with a = 12.510, b = 6.318, c = 8.561 Å, Z = 4. The structure, determined on the basis of three-dimensional Mo-Kα intensity data for 745 reflections refined to R = 0.10. The structure consists of ZnO4 tetrahedral chains along b joined by Si2O4 groups along a and c to form a three-dimensional network. Ca occurs in distorted CaO5(H2O) octahedra. The structure shows similarities to hemimorphite and Ca-Zn silicates but represents a unique tetrahedral framework.

The Outer Layered Suite of the Cuillin Igneous Complex (Isle of Skye, NW Scotland) comprises a Peridotite Series and a younger Allivalite Series (the latter comprising troctolites, eucrites and gabbros). Close to the junction between the Peridotite and the Allivalite Series (but wholly contained within the latter), an ultramafic breccia unit containing abundant peridotite xenoliths crops out. In the Peridotite Series, reddish-brown Cr-bearing spinels are present as disseminated crystals in the peridotite and also as chromitite seams, while in the peridotite xenoliths of the breccia unit, green pleonaste occurs in both of these modes of textural occurrence. Optical absorption spectroscopy reveals that the colour difference between the two spinel phases is related mainly to variable Al, Cr and Fe contents, while crystal structural analysis shows that the cooling rate calculated utilizing the oxygen positional parameter is comparable for all samples. The intracrystalline closure temperature for the Cr-spinel in the Peridotite Series is different for the disseminated and seam textural occurrences of the spinels, while the temperatures yielded by pleonaste in the peridotite xenoliths are the same for both textural occurrences. Our dataset suggests that the pleonaste in the peridotite xenoliths has been heated and equilibrated under subsolidus conditions, probably during breccia formation. During this heating, homogenization of the closure temperatures of pleonaste spinels occurred.

Proposal 16-C was accepted by the Commission on New Minerals and Mineral Names of the International Mineralogical Association, and parabariomicrolite is discredited as identical to hydrokenomicrolite-3R. There are now two type localities: Alto do Giz pegmatite, Equador Co., Rio Grande do Norte, Brazil and Volta Grande pegmatite, Nazareno, Minas Gerais, Brazil.