This work presents the results of an investigation of an assemblage of secondary Sc-minerals from the intraplutonic metaluminous pegmatite Kožichovice II, Třebíč Pluton, Czech Republic. The assemblage was formed by hydrothermally-induced dissolution of primary Sc-enriched (≈1.6 wt.% Sc2O3) columbite-(Mn) followed by in situ reprecipitation of volumetrically dominant fersmite (≈0.16 wt.% Sc2O3) and minor nioboheftetjernite (ScNbO4). Subsequent hydrothermal processes resulted in the formation of fluorcalciomicrolite + Sc-minerals (thortveitite + kristiansenite) + titanite. The mass balance calculations (based on EPMA-derived mineral compositions, mineral proportions obtained from TIMA automated mineralogy and textural observations) revealed that the amount of Sc released from the replaced mass of columbite-(Mn) is significantly higher than the amount of Sc incorporated in the mass of the secondary minerals. This indicates that part of the Sc was mobilised and released to the host rocks (pegmatite and granite). The secondary mineral assemblages indicate elevated Ca activity in the alteration fluids. Other occurrences of Sc-minerals in pegmatites (Baveno Pluton and Heftetjern pegmatite) show remarkable similarities in the paragenetic position of Sc-minerals (late hydrothermal/replacement minerals), including the high activity of Ca in fluids during their formation. The high activity of Ca in fluids during the metasomatic replacement of Sc-enriched precursors causes the formation of the volumetrically dominant Sc incompatible phases, followed by a local supersaturation of Sc resulting in the crystallisation of secondary Sc-minerals.

A new occurrence of berthierine has been found in the Pulsifer granitic pegmatite, near Auburn, Maine. Berthierine was found in miarolitic cavities (‘pockets’) as aggregates of radial platy crystals with albite, as fracture-fillings in microcline and as fine-grained anhedral flakes with muscovite. Berthierine samples from all associations are depleted in Mg, but show variable enrichment in Mn. The textural relationships of the berthierine assemblage indicate that its formation is probably related to the dissolution of microcline in the presence of a low-temperature, neutral to alkaline, Fe-rich hydrothermal solution. This mode of occurrence is in direct contrast to the typical formation of berthierine in granitic pegmatites that is generally related to the alteration of cordierite-group minerals.

The Maršíkov–Schinderhübel III pegmatite in the Hrubý Jeseník Mountains, Silesian Domain, Czech Republic, is a classic example of chrysoberyl-bearing LCT granitic pegmatite of beryl–columbite subtype. This thin pegmatite dyke, (up to 1 m in thickness in biotite–amphibole gneiss is characterised by symmetrical internal zoning. Tabular and prismatic chrysoberyl crystals (≤3 cm) occur typically in the intermediate albite-rich unit and rarely in the quartz core. Chrysoberyl microtextures are quite complex; their crystals are irregularly patchy, concentric or fine oscillatory zoned with large variations in Fe content (1.1–5.3 wt.% Fe2O3; ≤0.09 apfu). Chrysoberyl compositions reveal dominant Fe3+ = Al3+ and minor Fe2+ + Ti4+ = 2(Al, Fe)3+ substitution mechanisms in the octahedral sites. Tin, Ga, and V (determined by LA-ICP-MS) are characteristic trace elements incorporated in the chrysoberyl structure, whereas anomalously high Ta and Nb concentrations (thousands ppm) in chrysoberyl are probably caused by nano- to micro-inclusions of Nb–Ta oxide minerals; especially columbite–tantalite. Textural relationships between associated minerals, distinct schistosity of the pegmatite parallel to the host gneiss foliation and fragmentation of the pegmatite body into blocks as a result of superimposed stress are clear evidence for deformation and metamorphic overprinting of the pegmatite. Primary magmatic beryl, albite and muscovite were transformed to chrysoberyl, fibrolitic sillimanite, secondary quartz and muscovite during a high-temperature (~600°C) and medium-pressure (~250–500 MPa) prograde metamorphic stage under amphibolite-facies conditions. A subsequent retrograde, low-temperature (~200–500°C) and pressure (≤250 MPa) metamorphic stage resulted in the local alteration of chrysoberyl to secondary Fe,Na-rich beryl, euclase, bertrandite and late muscovite.

The paragenesis and composition of bavenite–bohseite were investigated in fifteen granitic pegmatites from the Bohemian Massif, Czech Republic. Three types distinct in their relation to primary Be precursors, mineral assemblages, morphology and origin were recognised: (1) primary hydrothermal bavenite–bohseite crystallised in miarolitic pockets from residual pegmatite fluids; and secondary bavenite–bohseite in two distinct types: (2) a proximal type restricted spatially to pseudomorphs after a primary Be mineral (beryl > phenakite, helvine–danalite); and (3) a distal type on brittle fractures and fissures of host pegmatite. The mineral assemblages are highly variable: (1) axinite-(Mn), smectite, calcite and pyrite; (2) bertrandite, milarite, secondary beryl, bazzite, K-feldspar, muscovite–illite, scolecite, gismondine-Ca, analcime, chlorite; and (3) muscovite, albite, quartz, epidote, pumpellyite-(Mg), pumpellyite-(Fe3+), titanite and chlorite. Electron microprobe analyses showed, in addition to major constituents (Si, Ca and Al), minor concentrations (in apfu) of Na (≤0.24), Fe (≤0.10), Mn (≤0.10) and F (≤0.36). The type 1 hydrothermal miarolitic bavenite–bohseite is mostly Al-rich (2.00–0.67 apfu) relative to type 2 proximal bavenite–bohseite and bohseite after beryl, phenakite and helvine–danalite (1.56–0.46, 0.70–0.05, 1.02–0.35 apfu, respectively); and type 3 distal bavenite–bohseite typically after beryl (1.63–0.09 apfu). Raman spectroscopy revealed that the distance between the OH– vibrational modes decreases with increasing bohseite component. The Al content of secondary type 2 proximal bavenite–bohseite is controlled by the composition of the Be precursor whereas type 3 distal bavenite–bohseite with beryl as the Be precursor is more variable and the composition is governed mainly by the composition of fluids. Calcium, a crucial component for bavenite–bohseite origins, was derived from residual pegmatite fluids (Vlastějovice, Vepice IV or Třebíč Plutons) or external sources (e.g. Drahonín IV, Věžná I or Maršíkov). Primary type 1 hydrothermal bavenite–bohseite from miarolitic pockets might have crystallised at T ≈ 300–400°C and P ≈ 200 MPa, whereas the secondary type 2 and 3 bavenite–bohseite formed at T ≈ 300–100°C and P ≈ 200–20 MPa.

Black tourmalines from seven granitic pegmatites (Golodnaya, Kazennitsa, Mokrusha, Kopi Mora, Zheltyye Yamy, Buzheninov Bor and Ministerskaya) related to the Murzinka pluton, Central Urals, Russia have been investigated using electron microprobe analysis, LA-ICP-MS, Raman and Mössbauer spectroscopy. Pegmatites are hosted by serpentinites and gneisses and are classified as schorl, oxy-schorl, fluor-schorl, dravite, oxy-dravite, foitite, oxy-foitite and darrellhenryite. The possible compositional evolution of tourmalines from the Ural pegmatites is as follows: Mg-rich dravite through to Fe-rich schorl, foitite and oxy-foitite to Fe- and Mn-rich darrellhenryite. The major substitutions in the tourmalines are: (1) Fe2+ ↔ Mg; (2) Al + WO2– ↔ Fe2+ + WOH–; (3) X-site vacancy + Al ↔ Na + Fe2+; (4) Al + WO2– ↔ Mg + WOH–; (5) X-site vacancy + Al ↔ Na + Mg; and (6) Fe ↔ Mn. Statical processing of the trace- and major-element composition distinguished three tourmaline groups: (1) trace Co, Ni, Pb, and major Ca and Mg; (2) uni-, di- and trivalent traces (Li, Zn, Ga) and di- and trivalent majors (Al, Mn); (3) U, Th, Hf, Ta, Nb, Y, In, and Sn which correspond to tri-, tetra-, and pentavalent high-field-strength elements. Mössbauer data shows the Fe3+/Fe2+ ratios in tourmalines from pegmatites hosted by gneisses (0.05–0.18) and serpentinites (0.28–0.65), indicates different oxidising environments. Raman data are consistent with the composition of the tourmalines.

The beryllium silicate minerals phenakite and bertrandite have been identified in granitic pegmatite dykes of the beryl-columbite subtype of Variscan age (~340−355 Ma), associated with S- to I-type granitic rocks of the Tatric Superunit, Western Carpathians (Slovakia). The two beryllium silicates and associated minerals were characterised by electron microprobe analysis, back-scattered electron petrography and cathodoluminescence imagery, X-ray diffraction and micro-Raman techniques. Phenakite and bertrandite form euhedral-to-anhedral crystals and aggregates in irregular domains and veinlets replacing primary magmatic beryl. A detailed textural study revealed a close genetic association of phenakite and bertrandite with secondary fine-grained quartz, K-feldspar and muscovite. Locally, clay phyllosilicate minerals, (with compositions similar to those of Fe-dominant hydrobiotite, beidellite, nontronite and saponite) occur as the youngest minerals. During the post-magmatic (hydrothermal) stage of the pegmatites, infiltration of aqueous K-bearing fluids at T ≈ 200–400°C resulted in the breakdown of magmatic beryl to secondary assemblages containing phenakite and bertrandite.

The Cape Cross–Uis pegmatite belt, Damara Orogen, north-central Namibia hosts multiple Ta–Nb- and Sn-oxide-bearing pegmatites. Columbite-group minerals, tapiolite, cassiterite and minor ixiolite and wodginite occur in abundance within pegmatites and display various compositional and internal structural mineralogical variations. Ta–Nb oxides display various zonation patterns indicative of multiple crystallisation phases, whereas cassiterite is dominantly homogeneous with minor euhedral columbite-group mineral inclusions. Ta–Nb oxides are mostly rich in Fe, with fractionation patterns in the columbite quadrilateral being sub parallel to the Ta/(Ta + Nb) axis; increasing Ta/(Ta + Nb) with little change in Mn/(Mn + Fe), which is consistent with classical trends in beryl-to-spodumene rare-element pegmatites. In addition, these trends suggest that co-crystallising minerals compete with Ta–Nb oxides for elements such as Mn, preventing Ta–Nb oxides from attaining Mn-rich compositions during the fractionation process. Cassiterite shows similar fractionation patterns with Fe > Mn and notable increases in the Ta content. Minor-element substitution in Ta–Nb oxides shows sharp decreases with increasing fractionation supporting the hypothesis that newly stabilised co-occurring minerals compete with columbite-group minerals for certain elements. Tapiolite shows the same minor-element trend, however, only for Sn and Ti suggesting cassiterite was a dominant competing mineral. Although crystallisation of Ta–Nb oxides from an aqueous fluid at the late-stages of pegmatite genesis is highly debated, significantly elevated Ta contents in metasomatised country rock, compared to unaltered country rock, may give new insight, suggesting that Ta may indeed partition into, and be transported by, an exsolved aqueous fluid. However, further studies of the country rock metasomatic contacts are required as currently the dataset is limited. The degree of fractionation as depicted by Ta–Nb and Sn oxides within pegmatites, indicate that a zonation from primitive to evolved pegmatites surrounding granites is not present and that pegmatites are probably not related to granites in the typical parent–daughter relationship.

Whiteite-(CaMnMn), CaMnMn2Al2[PO4]4(OH)2·8H2O, is a new hydrous phosphate of Ca, Mn and Al, which is closely related to both jahnsite-(CaMnMn) and the minerals of the whiteite group. It is monoclinic, P2/a, with a = 15.02(2), b = 6.95(1), c =10.13(3) Å, β = 111.6(1)°, V = 983.3(6) Å3, Z = 2 (from powder diffraction data) or a = 15.020(5), b = 6.959(2), c = 10.237(3) Å, β = 111.740(4)°,V = 984.3(5) Å3, Z = 2 (from single-crystal diffraction data). The mineral was found in the Hagendorf Süd granitic pegmatite (Germany) as small (up to 0.5 mm in size) crystals elongated on a and tabular on {010}. The crystals are either simply or polysyntheticallytwinned on {001}. They crystallize on the walls of voids within altered zwieselite crystals or form coronas (up to 1 mm in diameter) around cubic crystals of uraninite. The mineral is transparent, colourless to pale yellow (depending on Al–Fe3+ substitution), with a vitreouslustre and a white streak. The cleavage is perfect on {001}, the fracture is stepped and the Mohs hardness is 3½. In transmitted light, the mineral is colourless; dispersion was not observed. Whiteite-(CaMnMn) is biaxial (+), α = 1.589(2), β = 1.592(2), γ = 1.601(2)(589 nm), 2Vmeas = 60(10)°, 2Vcalc = 60.3°. The optical orientation is X = b, Z^a = 5°. The calculated and measured densities are D calc = 2.768 and D meas = 2.70(3) g cm–3, respectively.The mean chemical composition determined by electron microprobe is Na2O 0.53, MgO 0.88, Al2O3 11.66, P2O5 34.58, CaO 4.29, MnO 17.32, FeO 8.32, ZnO 2.60 wt.%, with H2O 19.50 wt.% (determined by the Penfield method), giving atotal of 99.68 wt.%. The empirical formula calculated on the basis of four phosphorus atoms per formula unit, with ferric iron calculated to maintain charge balance, is (Ca0.63Zn0.26Na0.14)Σ1.03(Mn0.60Fe0.40 2+)Σ1.00(Mn1.40Fe0.37 2+Mg0.18Fe0.06 3+)Σ2.01(Al1.88Fe0.12 3+)Σ2.00[PO4]4(OH)2·7.89H2O.The simplified formula is CaMnMn2Al2[PO4]4(OH)2·8H2O. The mineral is easily soluble in 10% HCl at room temperature. The strongest X-ray powder-diffraction lines [listed as d in Å (I) (hkl)]are as follows: 9.443(65)(001), 5.596(25)(011), 4.929(80)(210), 4.719(47)(002), 3.494(46)(400), 2.7958(100)(022). The crystal structure of whiteite-(CaMnMn) was refined for a single crystal twinned on (001) to R 1 = 0.068 on the basis of 5702 unique observed reflections. Itis similar to the structures of other members of the whiteite group. The mineral is named for the chemical composition, in accordance with whiteite-group nomenclature.

At the Morrua pegmatite, Mozambique, alkali feldspar has replaced pollucite under low-temperature (250–150°C) hydrothermal conditions. Fluids invading a fracture system in pollucite formed round granular aggregates of (K-Rb)-feldspar in three stages: (1) a compositionally heterogeneous core of the feldspar cluster (+cookeite ± apatite) with 7–20 mol.% RbAlSi3O8, grading outward into a Rb-dominant feldspar with 66 mol.% RbAlSi3O8 (20 wt.% Rb2O); (2) an intermediate layer of non-porous, inclusion-free, end-member K-feldspar; (3) an outer layer of porous end-member K-feldspar. Feldspars of all three stages seem to be monoclinic and disordered, with metastable sanidine structure. Zoning in K/Rb, preserved on a fine scale, was formed during growth at a temperature too low for subsequent alkali-cation diffusion or (Al,Si)-ordering.

The Koktokay No. 3 granitic pegmatite, Altai, northwestern China, is a strongly zoned rare-element granitic pegmatite, where the petrographic zones were distinguished into two groups: outer zones (I to IV) and inner zones (V to IX). Nb-Ta oxides and zircon are investigated in this paper by using quantitative electron-microprobe analyses (EMPA) and backscattered-electron (BSE) imaging. Columbite-tantalite and zircon occur in most textural zones, whereas tapiolite and uranmicrolite are mainly restricted to zone VII. Manganocolumbite and zircon from the outer zones (zones II and IV) are homogeneous except for a few exceptions, whereas manganotantalite and hafnian zircon from the inner zones (V–VII) are obviously heterogeneous and strongly zoned. Chemically, Ta/(Nb+Ta) in columbite-tantalite and Hf/(Zr+Hf) in zircon increase from the outer to the inner zones on one hand, and from core to rim in single zoned crystals on the other hand. Observations of intra-zonal variations of the chemical composition of Nb-Ta oxides and zircon in the Koktokay No. 3 granitic pegmatite may suggest that the outer zones crystallize under magmatic conditions, whereas the inner zones crystallize under fluid-rich magmatic conditions, and locally under hydrothermal conditions. The extreme enrichments of columbite-tantalite in Ta, and of zircon in Hf, as well as the occurrence of uranmicrolite and tapiolite, indicate an elevated evolution of the Koktokay No. 3 granitic pegmatite.

Materials designed for nuclear waste disposal include a range of ceramics, glass ceramics and glass waste forms. Those with crystalline phases have provided the momentum for studies of minerals as a means to understand aspects of waste-form crystal chemistry, behaviour in aqueous systems and radiation damage over geological periods of time. Although the utility of natural analogue studies varies, depending upon the degree of analogy to the proposed geological repository and other factors such as chemical composition, the available data suggest that Th-U host phases such as brannerite, monazite, pyrochlore, zircon and zirconolite are resistant generally to dissolution in aqueous fluids at low temperatures. Geochemical durability may or may not extend to hydrothermal systems depending on the specifics of fluid composition, temperature and pressure. At elevated temperatures, for example, davidite may break down to new phase assemblages including titanite, ilmenite and rutile. Perovskite is generally less resistant to dissolution at low temperatures and breaks down to TiO2, releasing A-site cations to the aqueous fluid. Studies of radiation damage indicate that the oxide and silicate phases become amorphous as a result of the gradual accumulation of alpha-recoil collision cascades. Monazite tends to remain crystalline on geological time scales, a very attractive property that potentially eliminates major changes in physical properties such as density and volume, thereby reducing the potential for cracking, which is a major concern for zircon. In spite of recent success in describing the behaviour of Th-U minerals in geological systems, considerable work remains in order to understand the P-T-X conditions during alteration and T-t history of the host rocks.

At Alijó-Sanfins there are many granitic aplite and pegmatite veins crosscutting different petrographic facies of the Hercynian granite batholith and also mica-schists. They are tin-bearing granitic rocks. Thirty-four samples of K-feldspar and 34 of albite from these veins and host granites were analysed to establish the distribution of elements and their fractionation trends in the sequence of feldspar crystallization. Rubidium and Cs increase, and Ba, Sr, Ba/K, Sr/K and K/Rb decrease in K-feldspar, whereas Na increases and Sr and Ca decrease in albite, from granites to aplites and pegmatites. In a few aplite-pegmatite veins Rb, Rb/Ba and Rb/Sr increase and Ba, Sr, K/Rb and Ba/Sr decrease in K-feldspar, and Rb increases and Sr decreases in albite from aplite to coexisting pegmatite. Equilibrium was not attained for trace elements between coexisting feldspars.