A rounded fragment of a multicoloured tourmaline crystal (2.5 cm diameter), collected from the secondary gem deposit of Mavuco, Alto Ligoña pegmatite district, Mozambique, has been investigated using a multi-analytical approach, with the objective of reconstructing its growth history. The sample represents a core-to-rim section, perpendicular to the c axis, of a crystal characterised by a variety of colours. These change from a black core to an intermediate zone with a series of colours, yellow, blue–green and purple, to a final dark-green prismatic overgrowth. These changes are the result of a wide variation in Fe, Mn, Ti and Cu concentrations and their redox state. The black core is characterised by enrichment in Fe and Mn, with iron present in its divalent state. The yellow zone shows a progressive depletion in Fe and its colouration is caused by Mn2+ and Mn2+-Ti4+ IVCT interactions. The progressive decrease in Mn coupled with the absence of Ti, and the lack of Fe, implies that Cu2+ acts as the only chromophore in the pale blue–green zone. The dominant colour-causing agent of the purplish zone is Mn3+, denoting a change in redox environment; however, even though the amount of Cu remains significant, its chromophore effect is obscured by Mn3+. The dark-green prismatic overgrowth, characterised by a sharp increase in Fe, Mn and also Ca, is interpreted as a late-stage partial re-opening of the geochemical system. This occurrence could potentially be related to mechanical instability of the cavity in which the crystal grew.

Fluor-rossmanite, ideally □(Al2Li)Al6(Si6O18)(BO3)3(OH)3F, is a new mineral of the tourmaline supergroup, found at the Krutaya pegmatite, Malkhan pegmatite field, Zabaykalskiy Krai, Western Siberia, Russia. It forms an intermediate zone up to 3 mm thick in a chemically heterogeneous, concentrically zoned, polychrome tourmaline crystal 3 × 2 cm in size. The new mineral is light pink, transparent with a white streak and a vitreous lustre. It is brittle, with conchoidal fracture. The Mohs hardness is 7. The Dmeas = 3.07(2) g cm–3 and Dcalc = 3.071 g cm–3. Optically, fluor-rossmanite is non-pleochroic, uniaxial (–), ω = 1.647(2) and ɛ = 1.628(2) (589 nm). The empirical formula calculated on the basis of 31 anions (O+OH+F) is: X(□0.46Na0.32Ca0.20Pb0.02)Σ1.00 Y(Al1.84Li1.05Mn0.05Fe2+0.02Ti0.02Cr0.01)Σ2.99 ZAl6.00 T(Si5.79Al0.21)Σ6.00B2.99O27 V(OH)3 W[F0.44(OH)0.20O0.36]Σ1.00. Fluor-rossmanite is trigonal, R3m; the unit-cell parameters are: a = 15.7951(3), c = 7.08646(17) Å, V = 1531.11(7) Å3 and Z = 3. The crystal structure is refined from single-crystal X-ray diffraction data [R = 0.0211 for 1178 unique reflections with I > 2σ(I)]. The new mineral is a ‘fluor-’ species belonging to the X-vacant group of the tourmaline supergroup. The closest end-member compositions of valid tourmaline species are those of rossmanite and fluor-elbaite, to which fluor-rossmanite is related by the substitutions WF– ↔ WOH– and X2□ + YAl3+ ↔ X2Na+ + YLi+, respectively.

The ancylite supergroup has been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association, with the general crystal chemical formula (M3+xM2+2–x)(CO3)2[(OH)x⋅(2–x)H2O] (1 ≤ x ≤ 2, Z = 2). The ancylite supergroup can be divided into two groups defined by different proportions of the M cation and hydroxyl anion and/or water molecule: the ancylite group is defined for 1 ≤ x ≤ 1.5; the kozoite group is defined for 1.5 < x ≤ 2. The ancylite supergroup minerals are orthorhombic with space group Pmcn, or monoclinic with space group Pm11, and have a crystal structure with species-defining trivalent and divalent M cations (M = La3+, Ce3+, Nd3+, Ca2+, Sr2+ and Pb2+) which centre ten-vertex polyhedra formed by oxygen atoms at three independent O sites. Two vertices of the triangular (CO3)2– anion are oxygen atoms, whereas the third one, O(3), is statistically filled with (OH)– groups and H2O molecules. The triangular faces of three oxygen atoms of MO10 coordination polyhedra join the chains of this ten-vertex polyhedron, which is extended along the c axis. The (CO3) triangles connect chains in three dimensions. To date, eight valid mineral species with M2+ = Sr2+, Ca2+ and Pb2+ belong to the ancylite group [ancylite-(La), ancylite-(Ce), calcioancylite-(La), calcioancylite-(Ce), calcioancylite-(Nd), gysinite-(La), gysinite-(Ce) and gysinite-(Nd)]. Two hydroxyl carbonates with only rare earth elements as species-defining cations, kozoite-(La) and kozoite-(Nd) are members of the kozoite group.

Valsassina (Lombardy, Northern Italy) is located in the Lombard Southern Alps and is characterised by the presence of a metamorphic basement, by a major late Variscan intrusive complex and by Carboniferous–Permian volcano-sedimentary cover units. These rocks host a pervasive system of inadequately studied mineralised veins. These veins are characterised by base metal (Pb, Zn, Cu and Fe) and complex polymetallic assemblages.

In this study, we have investigated the ore textures, mineral compositions of sulfides and sulfosalts (by EMPA–WDS and LA–ICP–MS analyses), and stable isotopes (C and O) in carbonate gangue minerals of various mineralised veins to determine the conditions of deposition of these ore deposits. Two different vein families can be recognised in Valsassina: NNW–SSE veins characterised by a complex polymetallic sulfide–sulfosalt assemblage, also with Ni–Co–Fe arsenides and other Ag–Bi-bearing minerals; and NE–SW veins with a simpler, base metal sulfide assemblage. The Ni–Co-bearing NNW–SSE veins have some distinctive features of the ‘five-element vein’ type deposits, with the Ni–Co–Fe arsenide ore stage pre-dating a sulfide-tetrahedrite-dominated ore stage. LA–ICP–MS data for pyrite and sphalerite, and stable isotopic compositions (C and O) of the carbonate gangue minerals, show no clear differences between the two families of veins, which are probably linked genetically. The isotopic compositions of the Valsassina vein carbonates are closely comparable with the signature of several major five-element ore districts. Preliminary temperature estimates for the Valsassina vein systems were based on the sphalerite composition, applying the GGIMFis geothermometer. The estimated temperatures for the sulfide-dominated ore stage post-dating the Ni–Co minerals precipitation range between 100 and 250°C. The crosscutting relationships, observed for all the veins with the host rocks, suggest a possible late to post Variscan (late Permian) age, making these vein systems comparable with other late–post Variscan polyphase hydrothermal events affecting large sectors of the Southern Alpine domain.