Explore the vast range of titles available.

Suenoite (IMA 2019-075), ideally □Mn2Mg5Si8O22(OH)2, is a new member of the amphibole supergroup discovered in the Mn ore deposit of Scortico–Ravazzone, Apuan Alps, Tuscany, Italy. It occurs as colourless tabular striated crystals, up to 0.1 mm in length, associated with spessartine and baryte. The streak is white, and the lustre is vitreous. Mohs hardness is estimated between 5.5 and 6. Cleavage is perfect on {210}. The calculated density is 3.283 g cm−3. Suenoite is optically biaxial (+), with α=1.655(5), β=1.660(5), and γ=1.670(5) (in white light). 2Vmeas is 75(10)°, and 2Vcalc is 70.9°. The orientation is X=a, Y=b, and Z=c. Pleochroism was not observed, as suenoite is colourless. The empirical chemical formula of suenoite is A(□0.91Ca0.07Na0.02)Σ1.00 B(Mn1.642+Fe0.362+)Σ2.00 C(Mg3.56Fe0.912+Mn0.612+Zn0.02)Σ5.10 T(Si7.86Al0.06)Σ7.92 O22 W[(OH)1.92F0.08]Σ2.00, and it is based on electron microprobe analyses, infrared spectroscopy, and Mössbauer spectroscopy. The unit-cell parameters of suenoite are a=18.7508(12), b=18.1396(12), c=5.3173(3) Å, and V=1808.6(2) Å3, with space group Pnma. The crystal structure was refined to R1=0.0490 for 2236 unique reflections with F>4σF and 194 refined parameters. The origin of suenoite is probably related to the recrystallisation of the Scortico–Ravazzone Mn ore deposit during the Tertiary tectono-metamorphic events, under greenschist-facies conditions, affecting the rocks belonging to the Alpi Apuane metamorphic complex.

Skogbyite, ideally Zr(Mg2Mn43+)SiO12, is a new mineral species (IMA 2023-085) within the braunite group, discovered in a complex metamorphic assemblage from the Långban Fe–Mn oxide deposit, Värmland County, Bergslagen ore province, Sweden. It is named after the Swedish mineralogist Henrik Skogby (b. 1956). The new mineral is hosted by a hausmannite–jacobsite-bearing calcite–dolomite–phlogopite rock that additionally contains pinakiolite, macedonite and sparse baddeleyite. In this assemblage, skogbyite occurs as very small, mostly ≤ 60 µm, rounded to subhedral grey crystals. It is suggested that skogbyite formed during regional metamorphism of a pre-existing, weakly Mn(–Fe)-mineralised carbonate–silicate rock. Optically, the mineral is opaque and bluish grey with a moderate reflectance in reflected polarised light and exhibits weak bireflectance and anisotropy. The Mohs hardness is estimated to be 6–6.5, and it has a calculated density of 4.821 g cm−3. Skogbyite is tetragonal, space group I41/acd, with unit-cell parameters a= 9.4914(4) Å, c= 18.9875(10) Å, V= 1710.52(17) Å3 and Z= 8. Its crystal structure was refined to R1= 0.0460 for 648 unique reflections with I > 2σI, collected utilising MoKα X-ray radiation. The five strongest (calculated) powder X-ray diffraction lines (d in Å, (I), (hkl)) are 2.740, (100), (224); 1.678, (31), (048); 1.431, (16), (264); 1.678, (13), (440); and 5.480, (12), (112). Electron probe microanalyses combined with single-crystal structure refinement resulted in the following empirical formula: (Zr0.694+Ce0.103+Mg0.06Ca0.01Zn0.01Pb0.01)Σ0.87(Mn4.233+Mg1.40Fe0.283+Al0.09)Σ6.00Si1.04O12 based on 12 O atoms. All Mn in the new mineral is trivalent. Skogbyite is related to gatedalite, Zr(Mn2Mn43+)SiO12, by the substitution Mn2+Mg−1. Skogbyite is abbreviated as “Skb”.

Biologically-controlled mineralization producing organic-inorganic composites (hard skeletons) by metazoan biomineralizers has been an evolutionary innovation since the earliest Cambrian. Among them, linguliform brachiopods are one of the key invertebrates that secrete calcium phosphate minerals to build their shells. One of the most distinct shell structures is the organo-phosphatic cylindrical column exclusive to phosphatic-shelled brachiopods, including both crown and stem groups. However, the complexity, diversity, and biomineralization processes of these microscopic columns are far from clear in brachiopod ancestors. Here, exquisitely well-preserved columnar shell ultrastructures are reported for the first time in the earliest eoobolids Latusobolus xiaoyangbaensis gen. et sp. nov. and Eoobolus acutulus sp. nov. from the Cambrian Series 2 Shuijingtuo Formation of South China. The hierarchical shell architectures, epithelial cell moulds, and the shape and size of cylindrical columns are scrutinised in these new species. Their calcium phosphate-based biomineralized shells are mainly composed of stacked sandwich columnar units. The secretion and construction of the stacked sandwich model of columnar architecture, which played a significant role in the evolution of linguliforms, is highly biologically controlled and organic-matrix mediated. Furthermore, a continuous transformation of anatomic features resulting from the growth of diverse columnar shells is revealed between Eoobolidae, Lingulellotretidae, and Acrotretida, shedding new light on the evolutionary growth and adaptive innovation of biomineralized columnar architecture among early phosphatic-shelled brachiopods during the Cambrian explosion.

The new tourmaline supergroup mineral dutrowite, Na(Fe2.52+Ti0.5)Al6(Si6O18)(BO3)3(OH)3O, has been discovered in an outcrop of a Permian metarhyolite near the hamlet of Fornovolasco, Apuan Alps, Tuscany, Italy. It occurs as chemically homogeneous domains, up to 0.5 mm, brown in colour, with a light-brown streak and a vitreous lustre, within anhedral to subhedral prismatic crystals, up to 1 mm in size, closely associated with Fe-rich oxy-dravite. Dutrowite is trigonal, space group R3m, with a=15.9864(8), c=7.2187(4) Å, V=1597.68(18) Å3, and Z=3. The crystal structure was refined to R1=0.0257 for 1095 unique reflections with Fo>4σ (Fo) and 94 refined parameters. Electron microprobe analysis, coupled with Mössbauer spectroscopy, resulted in the empirical structural formula X(Na0.81Ca0.20K0.01)Σ1.02 Y(Fe1.252+Mg0.76Ti0.56Al0.42)Σ3.00 Z(Al4.71Fe0.273+V0.023+Mg0.82Fe0.182+)Σ6.00 T[(Si5.82Al0.18)Σ6.00O18] (BO3)3O(3)(OH)3O(1)[O0.59(OH)0.41]Σ1.00, which was recast in the empirical ordered formula, required for classification purposes: X(Na0.81Ca0.20K0.01)Σ1.02 Y(Fe1.432+Mg1.00Ti0.56)Σ3.00 Z(Al5.13Fe0.273+V0.023+Mg0.58)Σ6.00 T[(Si5.82Al0.18)Σ6.00O18] (BO3)3V(OH)3 W[O0.59(OH)0.41]Σ1.00. Dutrowite is an oxy-species belonging to the alkali group of the tourmaline supergroup. Titanium is hosted in octahedral coordination, and its incorporation is probably due to the substitution 2Al3+ = Ti4+ + (Fe,Mg)2+. Its occurrence seems to be related to late-stage high-T/low-P replacement of “biotite” during the late-magmatic/hydrothermal evolution of the Permian metarhyolite.

Piccoliite, ideally NaCaMn 3+ 2 (AsO 4 ) 2 O(OH), is a new mineral discovered in the Fe–Mn ore hosted in metaquartzites of the Montaldo di Mondovì mine, Corsaglia Valley, Cuneo Province, Piedmont, Italy. It occurs as small and rare black crystals and aggregates hosted by a matrix of quartz, associated with calcite and berzeliite/manganberzeliite. It has been also found in the Valletta mine near Canosio, Maira Valley, Cuneo Province, Piedmont, Italy, where it occurs embedded in quartz associated with grandaite, hematite, tilasite/adelite and rarely thorianite. The mineral is opaque (thin splinters may be very dark red), with brown streak and has a resinous to vitreous lustre. It is brittle with irregular fracture. No cleavage has been observed. The measured Mohs hardness is ~5–5.5. Piccoliite is non fluorescent. The calculated density is 4.08 g⋅cm –3 . Chemical spot analyses by electron microprobe analysis using wavelength dispersive spectroscopy resulted in the empirical formula (based on 10 anions per formula unit) (Na 0.64 Ca 0.35 ) Σ0.99 (Ca 0.75 Na 0.24 ) Σ0.99 (Mn 3+ 1.08 Fe 3+ 0.59 Mg 0.20 Ca 0.10 ) Σ1.97 (As 2.03 V 0.03 Si 0.01 ) Σ2.07 O 9 (OH) and (Na 0.53 Ca 0.47 ) Σ1.00 (Ca 0.76 Na 0.23 Sr 0.01 ) Σ1.00 (Mn 3+ 0.63 Fe 3+ 0.49 Mg 0.48 Mn 4+ 0.34 Ca 0.06 ) Σ2.00 (As 1.97 P 0.01 Si 0.01 ) Σ1.99 O 9 (OH) for the Montaldo di Mondovì and Valletta samples, respectively. The mineral is orthorhombic, Pbcm , with single-crystal unit-cell parameters a = 8.8761(9), b = 7.5190(8), c = 11.689(1) Å and V = 780.1(1) Å 3 (Montaldo di Mondovì sample) and a = 8.8889(2), b = 7.5269(1), c = 11.6795(2) Å, V = 781.43(2) Å 3 (Valletta sample) with Z = 4. The seven strongest powder X-ray diffraction lines for the sample from Montaldo di Mondovì are [ d Å ( I rel ; hkl )]: 4.85 (57; 102), 3.470 (59; 120, 113), 3.167 (100; 022), 2.742 (30; 310, 213), 2.683 (53; 311, 023), 2.580 (50; 222, 114) and 2.325 (19; 320, 214, 223). The crystal structure ( R 1 = 0.0250 for 1554 unique reflections for the Montaldo di Mondovì sample and 0.0260 for 3242 unique reflections for the Valletta sample) has MnO 5 (OH) octahedra forming edge-shared dimers; these dimers are connected through corner-sharing, forming two-up-two-down [ [6] M 2 ( [4] T O 4 ) 4 φ 2 ] chains [ M = Mn; T = As; φ = O(OH)] running along [001]. These chains are bonded in the a and b directions by sharing corners with AsO 4 tetrahedra, giving rise to a framework of tetrahedra and octahedra hosting seven-coordinated Ca 2+ and Na + cations. The crystal structure of piccoliite is closely related to that of pilawite-(Y) as well as to carminite-group minerals that also show the same type of chains but with different linkage. The mineral is named after the mineral collectors Gian Paolo Piccoli and Gian Carlo Piccoli (father and son) (1926–1996 and b. 1953, respectively), the latter having discovered the type material at the Montaldo di Mondovì mine.

Sulfur belongs among H 2 O, CO 2 , and Cl as one of the key volatiles in Earth’s chemical cycles. High oxygen fugacity, sulfur concentration, and δ 34 S values in volcanic arc rocks have been attributed to significant sulfate addition by slab fluids. However, sulfur speciation, flux, and isotope composition in slab-dehydrated fluids remain unclear. Here, we use high-pressure rocks and enclosed veins to provide direct constraints on subduction zone sulfur recycling for a typical oceanic lithosphere. Textural and thermodynamic evidence indicates the predominance of reduced sulfur species in slab fluids; those derived from metasediments, altered oceanic crust, and serpentinite have δ 34 S values of approximately −8‰, −1‰, and +8‰, respectively. Mass-balance calculations demonstrate that 6.4% (up to 20% maximum) of total subducted sulfur is released between 30–230 km depth, and the predominant sulfur loss takes place at 70–100 km with a net δ 34 S composition of −2.5 ± 3‰. We conclude that modest slab-to-wedge sulfur transport occurs, but that slab-derived fluids provide negligible sulfate to oxidize the sub-arc mantle and cannot deliver 34 S-enriched sulfur to produce the positive δ 34 S signature in arc settings. Most sulfur has negative δ 34 S and is subducted into the deep mantle, which could cause a long-term increase in the δ 34 S of Earth surface reservoirs. Sulfur is one of the key volatiles in Earth’s chemical cycles; however, sulfur speciation, isotopic composition, and flux during the subduction cycle remain unclear. Here, the authors provide direct constraints on subduction zone sulfur recycling from high-pressure rocks and explore implications for arc magmatism.

Following the identification of a new occurrence of melanostibite from the Apuan Alps, the crystal chemistry of this mineral has been re-examined using specimens from its type locality, Sjögruvan, Örebro County, Sweden, and from the new occurrence, the Scortico–Ravazzone Mn ore deposit, Apuan Alps, Tuscany, Italy. Both specimens were examined through electron microprobe analysis, micro-Raman spectroscopy and single-crystal X-ray diffraction data; Mössbauer spectroscopy was used for the Swedish specimen. Electron microprobe data indicate a close to ideal composition Mn 2 Fe 3+ Sb 5+ O 6 for both samples, whereas Mössbauer spectroscopy confirmed the trivalent oxidation state of Fe. Single-crystal X-ray diffraction for the Swedish and Italian specimens points to the acentric nature of melanostibite, space group R 3. Refined unit-cell parameters of melanostibite from Scortico–Ravazzone and Sjögruvan are a = 5.2351(3), c = 14.3645(8) Å, V = 340.93(4) Å 3 , and a = 5.2314(2), c = 14.3518(8) Å, V = 340.15(3) Å 3 , respectively. Melanostibite is an homeotypic derivative of pyrophanite.

Much of the current volume of Earth’s continental crust had formed by the end of the Archaean eon 1 (2.5 billion years ago), through melting of hydrated basaltic rocks at depths of approximately 25–50 kilometres, forming sodic granites of the tonalite–trondhjemite–granodiorite (TTG) suite 2 – 6 . However, the geodynamic setting and processes involved are debated, with fundamental questions arising, such as how and from where the required water was added to deep-crustal TTG source regions 7 , 8 . In addition, there have been no reports of voluminous, homogeneous, basaltic sequences in preserved Archaean crust that are enriched enough in incompatible trace elements to be viable TTG sources 5 , 9 . Here we use variations in the oxygen isotope composition of zircon, coupled with whole-rock geochemistry, to identify two distinct groups of TTG. Strongly sodic TTGs represent the most-primitive magmas and contain zircon with oxygen isotope compositions that reflect source rocks that had been hydrated by primordial mantle-derived water. These primitive TTGs do not require a source highly enriched in incompatible trace elements, as ‘average’ TTG does. By contrast, less sodic ‘evolved’ TTGs require a source that is enriched in both water derived from the hydrosphere and also incompatible trace elements, which are linked to the introduction of hydrated magmas (sanukitoids) formed by melting of metasomatized mantle lithosphere. By concentrating on data from the Palaeoarchaean crust of the Pilbara Craton, we can discount a subduction setting 6 , 10 – 13 , and instead propose that hydrated and enriched near-surface basaltic rocks were introduced into the mantle through density-driven convective overturn of the crust. These results remove many of the paradoxical impediments to understanding early continental crust formation. Our work suggests that sufficient primordial water was already present in Earth’s early mafic crust to produce the primitive nuclei of the continents, with additional hydrated sources created through dynamic processes that are unique to the early Earth. Oxygen isotopes and whole-rock geochemistry show that the water required to make Earth’s first continental crust was primordial and derived from the mantle, not surface water introduced by subduction.

Lombardoite, ideally Ba 2 Mn 3+ (AsO 4 ) 2 (OH), and aldomarinoite, ideally Sr 2 Mn 3+ (AsO 4 ) 2 (OH), are two new minerals of the arsenbrackebuschite group in the brackebuschite supergroup, discovered in Fe–Mn ore in metaquartzites of the abandoned mine of Valletta, Canosio, Val Maira, Cuneo Province, Piedmont, Italy. They occur as red–brown and orange brown, respectively, as subhedral crystals (< 0.5 mm) in thin masses, associated with quartz, aegirine, baryte, calcite, hematite, muscovite and Mn minerals such as cryptomelane, braunite and manganberzeliite. Both minerals are translucent, have yellow–orange streak and vitreous lustre. Both are brittle. Estimated Mohs hardness is 6–6½ for lombardoite (by analogy to canosioite), and 4½–5 for aldomarinoite (by analogy to tokyoite). Calculated densities are 5.124 g/cm 3 for lombardoite and 4.679 g/cm 3 for aldomarinoite. Both minerals are biaxial (+). Lombardoite shows 2V z (meas.) = 78(4)° and is pleochroic with X = yellowish brown, Y = brown and Z = reddish brown ( Z > Y > X ). Aldomarinoite has 2V z (meas.) = 67.1(1)°, and is pleochroic with X = brown, Y = brownish orange and Z = yellowish brown ( Z > Y > X ). Point analyses by electron microprobe using wavelength dispersive spectroscopy resulted in the empirical formula (based on 9 O anions): (Ba 1.96 Sr 0.17 Pb 0.04 Na 0.02 Ca 0.02 ) Σ2.21 (Mn 3+ 0.62 Fe 3+ 0.13 Al 0.06 Mg 0.11 ) Σ0.92 [(As 0.87 V 0.12 P 0.01 ) Σ1.00 O 4 ] 2 (OH) for lombardoite, and (Sr 1.93 Ca 0.21 Ba 0.04 Pb 0.01 ) Σ2.19 (Mn 3+ 0.48 Al 0.35 Fe 3+ 0.21 Mg 0.01 ) Σ1.05 [(As 0.92 V 0.03 ) Σ0.95 O 4 ] 2 (OH) for aldomarinoite. The absence of H 2 O was confirmed by Raman spectroscopy and infrared spectroscopy. Both minerals are monoclinic, P 2 1 / m , with unit-cell parameters a = 7.8636(1) Å, b = 6.13418(1) Å, c = 9.1197(1) Å, β = 112.660(2)° and V = 405.94(1) Å 3 , for lombardoite and a = 7.5577(4) Å, b = 5.9978(3) Å, c = 8.7387(4) Å, β = 111.938(6)° and V = 367.43(3) Å 3 , for aldomarinoite. The eight strongest powder X-ray diffraction lines are [ d , Å ( I rel ) ( hkl )]: 6.985 (39) (10 $\\bar{1}$ ), 3.727 (33) (111), 3.314 (100) (21 $\\bar{1}$ ), 3.073 (24) (020), 3.036 (33) (21 $\\bar{2}$ , 10 $\\bar{3}$ ), 2.810 (87) (12 $\\bar{1}$ , 112), 2.125 (20) (301, 11 $\\bar{4}$ ) and 1.748 (24) (321) for lombardoite and 3.191 (89) (21 $\\bar{1}$ ), 2.997 (45) (020), 2.914 (47) (21 $\\bar{2}$ , 10 $\\bar{3}$ ), 2.715 (100) (112), 2.087 (39) (12 $\\bar{3}$ , 1.833 (32) (31 $\\bar{4}$ ), 1.689 (36) (321), 1.664 (21) (132) for aldomarinoite. The minerals are isostructural with brackebuschite: infinite chains of edge sharing octahedra running parallel to the b axis and decorated with AsO 4 groups are connected along the a and c axes through Ba and Sr atoms in lombardoite and aldomarinoite, respectively. The minerals are named after Bruno Lombardo (1944–2014), geologist and petrologist at C.N.R. (National Research Council of Italy), and Aldo Marino (b. 1942) the mineral collector and founding member of the AMI – Italian Micromineralogical Association.

Princivalleite, Na(Mn 2 Al)Al 6 (Si 6 O 18 )(BO 3 ) 3 (OH) 3 O, is a new mineral (IMA2020-056) of the tourmaline supergroup. It occurs in the Veddasca Valley, Luino area, Varese, Lombardy, Italy (46°03’30.74’’N, 8°48’24.47’’E) at the centre of a narrow (2–3 cm wide) vertical pegmatitic vein, a few metres long, crosscutting a lens of flaser gneiss. Crystals are subhedral (up to 10 mm in size), azure with a vitreous lustre, conchoidal fracture and white streak. Princivalleite has a Mohs hardness of ~7, a calculated density of 3.168 g/cm 3 and is uniaxial (–). Princivalleite has trigonal symmetry, space group R 3 m , a = 15.9155(2) Å, c = 7.11660(10) Å, V = 1561.15(4) Å 3 and Z = 3. The crystal structure was refined to R 1 = 1.36% using 1758 unique reflections collected with Mo K α X-ray intensity data. Crystal-chemical analysis resulted in the empirical crystal-chemical formula X (Na 0.54 Ca 0.11 □ 0.35 ) Σ1.00 Y (Al 1.82 Mn 2+ 0.84 Fe 2+ 0.19 Zn 0.07 Li 0.08 ) Σ3.00 Z (Al 5.85 Fe 2+ 0.13 Mg 0.02 ) Σ6.00 [ T (Si 5.60 Al 0.40 ) Σ6.00 O 18 ](BO 3 ) 3 O(3) [(OH) 2.71 O 0.29 ] Σ3.00 O(1) [O 0.66 F 0.22 (OH) 0.12 ] Σ1.00 which recast in its ordered form for classification purposes is: X (Na 0.54 Ca 0.11 □ 0.35 ) Σ1.00 Y (Al 1.67 Mn 2+ 0.84 Fe 2+ 0.32 Zn 0.07 Mg 0.02 Li 0.08 ) Σ3.00 Z Al 6.00 [ T (Si 5.60 Al 0.40 ) Σ6.00 O 18 ](BO 3 ) 3 V [(OH) 2.71 O 0.29 ] Σ3.00 W [O 0.66 F 0.22 (OH) 0.12 ] Σ1.00 . Princivalleite is an oxy-species belonging to the alkali group of the tourmaline supergroup. The closest end-member compositions of valid tourmaline species are those of oxy-schorl and darrellhenryite, to which princivalleite is related by the substitutions Mn 2+ ↔ Fe 2+ and Mn 2+ ↔ 0.5Al 3+ + 0.5Li + , respectively. Princivalleite from Veddasca Valley is a geochemical anomaly, originated in a B-rich and peraluminous anatectic pegmatitic melt formed in situ , poor in Fe and characterised by reducing conditions in the late-stage metamorphic fluids derived by the flaser gneiss. The Mn-enrichment in this new tourmaline is due to absence of other minerals competing for Mn such as garnet.