ALBERT

Description: In this issue This New Mineral Names has entries for 21 new minerals, including alexkhomyakovite, andreadiniite, arsenmedaite, barwoodite, bodieite, ciriottiite, clino-oscarkempffite, ferrovorontsovite, ilirneyite, kannanite, magnesiohornblende, merelaniite, oyonite, pararaisaite, petříčekite, quijarroite, staročeskéite, tantalowodginite, topsøeite, tsygankoite, and vorontsovite.

Description: A high-pressure single-crystal X-ray diffraction (XRD) study has been carried out on two natural zoisite samples Ca2Al3−xFexSi3O12OH, one Fe-free (x = 0) and one Fe-rich (x = 0.12). The unit-cell parameters were determined for the Fe-free sample at 18 different pressures up to 7.76 GPa and for the Fe-rich sample at 13 different pressures up to 7.63 GPa. The P(V) data for both of the samples were fitted by a third-order Birch-Murnaghan equation of state (BM3 EoS). The equation of state coefficients are: V0 = 903.39(5) Å3, KT0 = 122.1(7) GPa, and K′0 = 6.8(2) for the Fe-free sample and V0 = 906.95(5) Å3, KT0 = 119.1(7) GPa, and K′0 = 7.3(2) for the Fe-rich sample. This shows that the addition of Fe in to the crystal structure of zoisite leads to a slight softening of the structure.Both compositions exhibit axial compressibilities βc 〉 βa 〉〉 βb, with the compressibilities of the a and b axes of the two samples being indistinguishable. The softening of the bulk modulus of zoisite with Fe content follows from softening of the c-axis of the structure. A high-pressure structural study of the Fe-free sample showed that the main compression mechanisms in the structure are the compression of soft inter-octahedral distance along [001] and soft intra-octahedral distances along [010] directions, while along [100] the main compression occurs because of the compression of stiff intra-octahedral distances. The substitution of Fe on to the M3 octahedral site of the structure leads to an increase of the intra-octahedral distance of the M3 that triggers the rotation of M12 and therefore leads to the softening of the M12 inter-octahedral distances that accounts for the softening of the c-axis of the structure.

Description: The high-pressure elastic behavior and the P-induced structure evolution of a natural cancrinite from Cameroun {Na6.59Ca0.93[Si6Al6O24](CO3)1.04F0.41·2H2O, a = 12.5976(6) Å, c = 5 .1168(2) Å, space group: P63} were investigated by in situ single-crystal X-ray diffraction under hydrostatic conditions up to 6.63(2) GPa with a diamond-anvil cell. The P-V data were fitted with an isothermal Birch-Murnaghan type equation of state (BM EoS) truncated to the third order. Weighted fit (by the uncertainty in P and V) gave the following elastic parameters: V0 = 702.0(7) Å3, KV0 = 51(2) GPa, and KV′ = 2.9(4). A linearized BM EoS was used to fit the a-P and c-P data, giving the following refined parameters: a0 = 12.593(5) Å, Ka0 = 64(4) GPa, Ka′ = 4.5(9), for the a-axis, and c0 = 5.112(3) Å, Kc0 = 36(1) GPa, Kc′ = 1.9(3) for the c-axis (elastic anisotropy: Ka0:Kc0 = 1.78:1). A subtle change of the elastic behavior appears to occur at P 〉 4.62 GPa, and so the elastic behavior was also described on the basis of BM EOS valid between 0.0001–4.62 and 5.00–6.63 GPa, respectively. The high-pressure structure refinements allowed the description of the main deformation mechanisms responsible for the anisotropic compression of cancrinite on (0001) and along [0001]. A comparative analysis of the structure evolution in response of the applied pressure and temperature of isotypic materials with cancrinite-like topology is carried out.

Description: A single-crystal X-ray diffraction (XRD) study, using a diamond-anvil cell at high pressure and room temperature, was performed on a crystal from a natural space group P2/n omphacite sample with composition very close to Jd55Di45 and with a high degree of order in cation distribution. Unit-cell parameters were determined at 13 different pressures up to about 7.5 GPa. A third-order Birch-Murnaghan equation of state (BM3-EoS) fitted to the P-V data yielded V0 = 421.43(4) Å3, KT0 = 122(1) GPa, and K' = 5.1(3). The KT0 value for this sample lies between the data obtained for the two end-members jadeite and diopside, and describes a slight positive curvature trend.During the same experiment, intensity data were collected and crystal structures were refined at 5 pressures up to 7.3 GPa. Both M1 and M2 polyhedra volumes showed a slight but significant change in slope at about 4 GPa. This behavior can likely be explained in terms of tilt angle variation of TA and TB tetrahedral, which also showed a change in slope with pressure, rather than in terms of bond length compression anomaly.

Description: 〈div data-abstract-type="normal"〉〈p〉The new mineral fluorarrojadite-(BaNa), ideally BaNa〈span〉4〈/span〉CaFe〈span〉13〈/span〉Al(PO〈span〉4〈/span〉)〈span〉11〈/span〉(PO〈span〉3〈/span〉OH)F〈span〉2〈/span〉 was found on the dump of Elisabeth adit near Gemerská Poloma, Slovakia. It occurs in hydrothermal quartz veins intersecting highly fractionated, topaz–zinnwaldite S-type leucogranite. Fluorarrojadite-(BaNa) is associated with fluorapatite, ‘fluordickinsonite-(BaNa)’, triplite, viitaniemiite and minor amounts of other minerals. It forms fine-grained irregular aggregates up to 4 cm x 2 cm, which consist of individual anhedral grains up to 0.01 mm in size. It has a yellowish-brown to greenish-yellow colour, very pale yellow streak and a vitreous to greasy lustre. Mohs hardness is ~4½ to 5. The fracture is irregular and the tenacity is brittle. The measured density is 3.61(2) g cm〈span〉–3〈/span〉 and calculated density is 3.650 g cm〈span〉–3〈/span〉. Fluorarrojadite-(BaNa) is biaxial (+) and nonpleochroic. The calculated refractive index based on empirical formula is 1.674. The empirical formula (based on 47 O and 3 (OH + F) apfu) is 〈span〉A1〈/span〉(Ba〈span〉0.65〈/span〉K〈span〉0.35〈/span〉)〈span〉Σ1.00〈/span〉 〈span〉A2〈/span〉Na〈span〉0.35〈/span〉 〈span〉B1〈/span〉(Na〈span〉0.54〈/span〉Fe〈span〉0.46〈/span〉)〈span〉Σ1.00〈/span〉 〈span〉B2〈/span〉Na〈span〉0.54〈/span〉〈span〉Ca〈/span〉(Ca〈span〉0.74〈/span〉Sr〈span〉0.20〈/span〉Pb〈span〉0.02〈/span〉Ba〈span〉0.04〈/span〉)〈span〉Σ1.00〈/span〉Na〈span〉2〈/span〉 〈span〉Na3〈/span〉Na〈span〉0.46〈/span〉 〈span〉M〈/span〉(Fe〈span〉7.16〈/span〉Mn〈span〉5.17〈/span〉Li〈span〉0.37〈/span〉Mg〈span〉0.12〈/span〉Sc〈span〉0.08〈/span〉Zn〈span〉0.06〈/span〉Ga〈span〉0.02〈/span〉Ti〈span〉0.02〈/span〉)〈span〉Σ13.00〈/span〉 Al〈span〉1.02〈/span〉P〈span〉11〈/span〉O〈span〉44〈/span〉PO〈span〉3.46〈/span〉(OH)〈span〉0.54〈/span〉 〈span〉W〈/span〉(F〈span〉1.54〈/span〉OH〈span〉0.46〈/span〉). Fluorarrojadite-(BaNa) is monoclinic, space group 〈span〉Cc〈/span〉, 〈span〉a〈/span〉 = 16.563(1) Å, 〈span〉b〈/span〉 = 10.0476(6) Å, 〈span〉c〈/span〉 = 24.669(1) Å, β = 105.452(4)°, 〈span〉V〈/span〉 = 3957.5(4) Å〈span〉3〈/span〉 and 〈span〉Z〈/span〉 = 4. The seven strongest reflections in the powder X-ray diffraction pattern are [〈span〉d〈/span〉〈span〉obs〈/span〉 in Å, (I), 〈span〉hkl〈/span〉]: 3.412, (21), 116; 3.224, (37), 206; 3.040, (100), 42〈span〉〈span〉〈img data-mimesubtype="gif" data-type="simple" src="http://static.cambridge.org/resource/id/urn:cambridge.org:id:binary:20181017132303927-0397:S0026461X18000166:S0026461X18000166_inline1.gif"〉 〈span data-mathjax-type="texmath"〉 〈/span〉 〈/span〉〈/span〉; 2.8499, (22), 33〈span〉〈span〉〈img data-mimesubtype="gif" data-type="simple" src="http://static.cambridge.org/resource/id/urn:cambridge.org:id:binary:20181017132303927-0397:S0026461X18000166:S0026461X18000166_inline2.gif"〉 〈span data-mathjax-type="texmath"〉 〈/span〉 〈/span〉〈/span〉; 2.7135, (56), 226; 2.5563, (33), 028 and 424; 2.5117, (23), 040. The new mineral is named according to the nomenclature scheme of arrojadite-group minerals, approved by the IMA CNMNC. In fluorarrojadite-(BaNa), Fe〈span〉2+〈/span〉 is a dominant cation at the 〈span〉M〈/span〉 site (so the root-name is arrojadite) and two suffixes are added to the root-name according to the dominant cation of the dominant valence state at the 〈span〉A〈/span〉1 (Ba〈span〉2+〈/span〉) and 〈span〉B〈/span〉1 sites (Na〈span〉+〈/span〉). A prefix fluor is added to the root-name as F〈span〉–〈/span〉 is dominant over (OH)〈span〉–〈/span〉 at the 〈span〉W〈/span〉 site.〈/p〉〈/div〉

Description: Langhofite, ideally Pb2(OH)[WO4(OH)], is a new mineral from the Långban mine, Värmland, Sweden. The mineral and its name were approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA2019-005). It occurs in a small vug in hematite–pyroxene skarn associated with calcite, baryte, fluorapatite, mimetite and minor sulfide minerals. Langhofite is triclinic, space group P$ ar{1}$, and unit-cell parameters a = 6.6154(1) Å, b = 7.0766(1) Å, c = 7.3296(1) Å, α = 118.175(2)°, β = 94.451(1)°, γ = 101.146(1)° and V = 291.06(1) Å3 for Z = 2. The seven strongest Bragg peaks from powder X-ray diffractometry are [dobs, Å (I)(hkl)]: 6.04(24)(010), 3.26(22)(11$ ar{2}$), 3.181(19)(200), 3.079(24)(1$ ar{1}$2), 3.016(100)(020), 2.054(20)(3$ ar{1}$1) and 2.050(18)(13$ ar{2}$). Langhofite occurs as euhedral crystals up to 4 mm, elongated along the a axis, with lengthwise striation. Mohs hardness is ca. 2½, based on VHN25 data obtained in the range 130–192. The mineral is brittle, with perfect {010} and {100} cleavages. The calculated density based on the ideal formula is 7.95(1) g⋅cm–3. Langhofite is colourless to white (non-pleochroic) and transparent, with a white streak and adamantine lustre. Reflectance curves show normal dispersion, with maximum values 15.7–13.4% within 400–700 nm. Electron microprobe analyses yield only the metals Pb and W above the detection level. The presence of OH-groups is demonstrated with vibration spectroscopy, from band maxima present at ~3470 and 3330 cm–1. A distinct Raman peak at ca. 862 cm–1 is related to symmetric W–oxygen stretching vibrations. The crystal structure is novel and was refined to R = 1.6%. It contains [W2O8(OH)2]6– edge-sharing dimers (with highly distorted WO6-octahedra) forming chains along [101] with [(OH)2Pb4]6+ dimers formed by (OH)Pb3 triangles. Chains configure (010) layers linked along [010] by long and weak Pb–O bonds, thus explaining the observed perfect cleavage on {010}. The mineral is named for curator Jörgen Langhof (b. 1965), who collected the discovery sample.