Polysynthetic Twinning in RbIn3S5

2002 ◽  
Vol 167 (1) ◽  
pp. 214-225 ◽  
Author(s):  
L. Kienle ◽  
A. Simon
Keyword(s):  
Polysynthetic Twinning

The unit cell of talc

1978 ◽  
Vol 42 (321) ◽  
pp. 107-110 ◽  
Author(s):  
M. Akizuki ◽  
J. Zussman
Keyword(s):  
Electron Microscope ◽  
Layered Structure ◽  
Stacking Faults ◽  
Unit Cell ◽  
Lattice Imaging ◽  
Polysynthetic Twinning ◽  
The Common

SummarySix specimens of talc studied by the electron microscope lattice-imaging and diffraction techniques were found to have the triclinic one-layer (1 Tr) structure. Since no evidence of a monoclinic two-layered structure was found in any specimen it is concluded that the 1 Tr structure is the common one for talc, and it may, moreover, be the only one. Extremely fine polysynthetic twinning and single intrinsic stacking faults were found in talc.

Definitive data on bohdanowiczite, a new silver bismuth selenide

1979 ◽  
Vol 43 (325) ◽  
pp. 131-133 ◽  
Author(s):  
M. Banaś ◽  
D. Atkin ◽  
J. F. W. Bowles ◽  
P. R. Simpson
Keyword(s):  
Additional Data ◽  
Hexagonal Lattice ◽  
New Mineral ◽  
Calculated Density ◽  
Yellow Colour ◽  
Cell Parameters ◽  
Reflected Light ◽  
Polysynthetic Twinning ◽  
Polymetallic Mineralization ◽  
A New Species

SummaryBohdanowiczite was first described in 1967 but incomplete data prevented its acceptance as a new mineral at that time. Additional data on the same material now characterize bohdanowiczite as a new species with the formula:3[(Ag0.98Cu0.02)0.97(Bi0.97Pb0.03)1.02(Se0.83S0.17)2.01]The mineral occurs in intimate intergrowths with clausthalite and wittichenite in polymetallic mineralization at Kletno in Poland. In reflected light bohdanowiczite has a creamy-yellow colour and short polysynthetic twinning is frequently observed. Cell parameters indexed on a hexagonal lattice are a = 4.183±0.008 Å and c = 19.561± 0.016 Å. Pm1 is the most likely space group. The strongest lines of the powder pattern are 2.91(100), 2.03(30), 3.40(20), 6.54(20), 2.09(18), 3.26(18). The calculated density is 7.72 gm/cm3 and the VHN between 63 and 96 kg/mm2.

Palladium arsenide-antimonides from habira, Minas Gerais, Brazil

1974 ◽  
Vol 39 (305) ◽  
pp. 528-543 ◽  
Author(s):  
A. M. Clark ◽  
A. J. Criddle ◽  
E. E. Fejer
Keyword(s):  
Minas Gerais ◽  
Powder Pattern ◽  
Weak Anisotropy ◽  
Yellow Colour ◽  
Space Group ◽  
Pale Yellow Colour ◽  
Reflected Light ◽  
Cell Dimensions ◽  
Polysynthetic Twinning ◽  
Reflectance Measurements

SummaryThe arsenopalladinite concentrates from Itabira, Minas Gerais, Brazil, have been found to contain three arsenide-antimonides of palladium, namely arsenopalladinite, atheneïte, and isomertieite. The second and third of these are new minerals.Arsenopalladinite, redefined, is Pd5(As,Sb)2 and triclinic with a 7·399, b 14·063, c 7·352 Å, α 92° 03′, β 118° 57′, γ 95° 54′. Z = 6. Dmeas = 10·4, Dcalc = 10sd46. In reflected light arsenopalladinite is white with a yellowish creamy hue. The mineral shows complex polysynthetic twinning and is strongly anisotropic. Reflectance measurements at 470, 546, 589, and 650 nm respectively gave: in air, 46·67–48·86, 49·97–52·90, 52·82–54·96, and 55·61–57·72 in oil, 32·30–35·07, 37·12–39·40, 38·97–41·32, and 40·28–43·07. VHN100 379–449, av. 407.Atheneïte, (Pd, Hg)3As, is hexagonal, space group P6/mmm and cell dimensions a 6·798, c 3·483 Å. The strongest lines of the powder pattern are 2·423 vvs (111) , 2·246 vs (201), 1·371 s (212), 1·302 s (302), 1·259 s (321). Z =2. Dcalc = 10·16. In reflected light atheneïte is white with a faint bluish tint compared to arsenopalladinite. Anisotropy distinct. Untwinned. Reflectivities for the two grains examined are: in air, 470 nm 47·51–54·75, 47·43–51·18; 546 nm 50·79–58·01, 51·36–54·36; 589 nm 53·13–61·01, 53·24–55·86; 650 nm 55·94–63·13, 54·76–56·77; in oil, 470 nm 30·03–43·67, 33·46–37·31; 546 nm 33·42–47·75, 37·64–41·07; 589 nm 35·80–49·04, 39·40–42·24; 650 nm 38·25–50·49, 41·07–42·85. VHN100 419–442, av. 431.Isomertieite, (Pd,Cu)5(Sb,As)2, is cubic, space group Fd3m, a 12·283 Å. The strongest lines of the powder pattern are 2·356 vs (333, 511), 2·167 vvs (440), 0·8599 s (10.10.2, 14.2.2), 0·8206 s (12.8.4), 0·7996 s (10.10.6, 14.6.2), 0·7881 s (999, 1.11.1, 13·7·5, 15·3·3), 0·7801 s (12.10.2, 14.6.4). Z = 16. Dcalc = 10·33. In reflected light isomertieite is a pale yellow colour. One grain was isotropic, three others displayed weak anisotropy. Untwinned. Reflectance measurements at 470, 546, 589, and 650 nm gave respectively: in air, 44·74–46·46, 52·23–53·25, 55·05-57·49, 56·97–62·03; in oil, 31·04–31·40, 38·42–38·90, 40·80–42·16, and 42·91–45·63. VHN100 587–597, av. 592.Quantitative colour values are also given, and the chemical and optical properties are compared with the related mineral, stibiopalladinite.

Polysynthetic Twinning in Poly(vinylcyclohexane) Single Crystals and “Fractional” Secondary Nucleation in Polymer Crystal Growth

2006 ◽  
Vol 39 (3) ◽  
pp. 1008-1019 ◽  
Author(s):  
Daniel Alcazar ◽  
Jrjeng Ruan ◽  
Annette Thierry ◽  
Akiyoshi Kawaguchi ◽  
Bernard Lotz
Keyword(s):  
Crystal Growth ◽  
Single Crystals ◽  
Secondary Nucleation ◽  
Polymer Crystal ◽  
Polysynthetic Twinning

Naldrettite, Pd2Sb, a new intermetallic mineral from the Mesamax Northwest deposit, Ungava region, Québec, Canada

2005 ◽  
Vol 69 (1) ◽  
pp. 89-97 ◽  
Author(s):  
L. J. Cabri ◽  
A. M. McDonald ◽  
C. J. Stanley ◽  
N. S. Rudashevsky ◽  
G. Poirier ◽  
...  
Keyword(s):  
New Mineral ◽  
Indentation Hardness ◽  
Fold Belt ◽  
Orthorhombic Space Group ◽  
Equivalent Circle Diameter ◽  
Sulphide Minerals ◽  
Polysynthetic Twinning ◽  
Monoclinic Pyrrhotite ◽  
Micro Indentation ◽  
Circle Diameter

AbstractNaldrettite, Pd2Sb, is a new intermetallic mineral discovered in the Mesamax Northwest deposit, Cape Smith fold belt, Ungava region, northern Québec. It is associated with monoclinic pyrrhotite, pentlandite, chalcopyrite, galena, sphalerite, cobaltite, clinochlore, magnetite, sudburyite (PdSb), electrum and altaite. Other rarer associated minerals include a second new mineral (ungavaite, Pd4Sb3), sperrylite (PtAs2), michenerite (PdBiTe), petzite (Ag3AuTe4) and hessite (Ag2Te). Naldrettite occurs as anhedral grains, which are commonly attached or moulded to sulphide minerals, and also associated with clinochlore. Grains of naldrettite vary in size (equivalent circle diameter) from ~10 to 239 μm, with an average of 74.4 mm (n = 632). Cleavage was not observed and fracture is irregular. The mineral has a mean micro-indentation hardness of 393 kg/mm2. It is distinctly anisotropic, non-pleochroic, has weak bireflectance, and does not exhibit discernible internal reflections. Some grains display evidence of strain-induced polysynthetic twinning. Naldrettite appears bright creamy white in association with pentlandite, pyrrhotite, clinochlore and chalcopyrite. Reflectance values in air (and in oil) for R1 and R2 are: 49.0, 50.9 (35.9, 37.6) at 470 nm, 53.2, 55.1 (40.3, 42.1) at 546 nm, 55.4, 57.5 (42.5, 44.3) at 589 nm and 58.5, 60.1 (45.4, 47.2) at 650 nm. The average of 69 electron-microprobe analyses on 19 particles gives: Pd 63.49, Fe 0.11, Sb 35.75, As 0.31, and S 0.02, total 99.68 wt.%, corresponding to (Pd1.995Fe0.007)2.002(Sb0.982AS0.014S0.002)0.998. The mineral is orthorhombic, space group Cmc21, a 3.3906(1), b 17.5551(5), c 6.957(2) Å , V 414.097(3) Å3, Z = 8. Dcalc is 10.694(1) g/cm3. The six strongest lines in the X-ray powder-diffraction pattern [d in Å (I)(hkl)] are: 2.2454(100)(132), 2.0567(52)(043), 2.0009(40)(152), 1.2842(42)(115), 1.2122(50)(204) and 0.8584(56)(1.17.4).

Coquandite, Sb6O8(SO4).H2O, a new mineral from Pereta, Tuscany, Italy, and two other localities

1992 ◽  
Vol 56 (385) ◽  
pp. 599-603 ◽  
Author(s):  
C. Sabelli ◽  
P. Orlandi ◽  
G. Vezzalini
Keyword(s):  
Cell Volume ◽  
Empirical Formula ◽  
Twin Plane ◽  
New Mineral ◽  
Chemical Analyses ◽  
Calculated Density ◽  
X Ray ◽  
A Cell ◽  
Polysynthetic Twinning ◽  
Lamellar Crystals

AbstractCoaquandite, a new antimony oxy-sulphate hydrate, occurs as spheroidal knobs of silky fibres or, rarely, as tiny transparent colourless lamellar crystals on stibnite at the Pereta mine, Tuscany, Italy; it is associated with klebelsbergite, peretaite, valentinite, sulfur, gypsum, stibiconite, and senarmontite. Coquandite is triclinic P1, with a 11.434(7), b 29.77(4), c 11.314(4) Å, α 91.07(7)°, β 119.24(3)° γ 92.82(1)° . It has a cell volume of 3352(5)Å3 with Z = 12 and a calculated density of 5.78 g cm−3. The crystals, elongated along [001] and flattened on {010}, display polysynthetic twinning with (010) as the twin plane. Optically, they are biaxial (+) with z ≈ c, 2V ≫ 60° n = 2.08(5). The strongest lines of the X-ray powder pattern are [d in Å, (I), (hkl)] 14.84(50)(020), 9.27(41)(111, 110), 6.81(67)130, 3.304(93)(090), 3.092(100)(330).Coquandite has also been found at the Cetine mine, Tuscany, Italy, and at the Lucky Knock mine, Tonasket, Okanogan County, Washington, USA. 22 microprobe chemical analyses (elemental microanalysis for H) gave Sb2O3 88.91, SO3 8.35, CaO 0.04, Na2O 0.03, H2O 1.43, total 98.76 wt.%, corresponding to the empirical formula (Sb + S = 7) Sb5.98Ca0.01Na0.01O7.96(SO4)1.02.0·78H2O, and to the idealised formula Sb6O8(SO4).H2O. The I.R. spectrum, which confirms the presence of water in the formula, is given.A partial structural arrangement is also given: the Sb polyhedra lie in nine layers perpendicular to [010] and form 'hexagonally' shaped groups surrounded by SO4 tetrahedra.

Jinshajiangite: structure, twinning and pseudosymmetry

2018 ◽  
Vol 74 (4) ◽  
pp. 325-336 ◽  
Author(s):  
Shiyun Jin ◽  
Huifang Xu ◽  
Seungyeol Lee ◽  
Pingqiu Fu
Keyword(s):  
Structure Model ◽  
X Ray Diffraction ◽  
Silicate Mineral ◽  
Titanium Silicate ◽  
X Ray ◽  
Space Groups ◽  
Cation Layer ◽  
Transmission Electron ◽  
Polysynthetic Twinning ◽  
Polytype Structure

The crystal structure of jinshajiangite based on a sample from its original discovery location is studied using single-crystal X-ray diffraction and transmission electron microscopy methods. Jinshajiangite is a titanium silicate mineral with an ideal chemical formula of BaNaFe4Ti2(Si2O7)2O2(OH)2F. The structure of jinshajiangite is of P\bar 1 symmetry (triclinic system), with a = 8.7331 (2) Å, b = 8.7366 (2) Å, c = 11.0404 (3) Å, α = 81.477 (1)°, β = 110.184 (1)°, γ = 104.384 (1)° and V = 764.03 (3) Å3, instead of the previously proposed C\bar 1 cell [a = 10.7059 (5) Å, b = 13.7992 (7) Å, c = 20.760 (1) Å, α = 90.008 (1)°, β = 94.972 (1)°, γ = 89.984 (1)°, V = 3055.4 (4) Å3]. The basic topology of the new structure is similar to the previously proposed C\bar 1 structure, except there is only one type of titanium silicate and intermediate cation layer in the structure (instead of two types), which are all related by the translation along the c-axis. Even though there is a significant amount of Mn in the chemical composition, no obvious ordering between Fe and Mn is observed in the structure. All the mineral species of the perraultite-type structure (jinshajiangite, perraultite, surkhobite and bobshannonite) should have the same P\bar 1 structure as jinshajiangite with ∼10 Å d 001 spacing, and all the previously proposed monoclinic space groups were pseudosymmetry generated by nanoscale polysynthetic twinning on the (001) composition plane. The similar phenomenon observed in bafertisite is also discussed in the paper with an alternative polytype structure model proposed.

A new mineral, chrisstanleyite, Ag2Pd3Se4, from Hope's Nose, Torquay, Devon, England

1998 ◽  
Vol 62 (2) ◽  
pp. 257-264 ◽  
Author(s):  
W. H. Paar ◽  
A. C. Roberts ◽  
A. J. Criddle ◽  
D. Topa
Keyword(s):  
New Mineral ◽  
History Museum ◽  
X Ray ◽  
International Mineralogical Association ◽  
Reflected Light ◽  
Mohs Hardness ◽  
Polysynthetic Twinning ◽  
The Mean ◽  
Gold Bearing ◽  
The Ideal

AbstractChrisstanleyite, Ag2Pd3Se4, is a new mineral from gold-bearing carbonate veins in Middle Devonian limestones at Hope's Nose, Torquay, Devon, England. It is associated with palladian and argentian gold, fischesserite, clausthalite, eucairite, tiemannite, umangite, a Pd arsenide-antimonide (possibly mertieite II), cerussite, calcite and bromian chlorargyrite. Also present in the assemblage is a phase similar to oosterboschite, and two unknown minerals with the compositions, PdSe2 and HgPd2Se3. Chrisstanleyite occurs as composite grains of anhedral crystals ranging from a few µm to several hundred µm in size. It is opaque, has a metallic lustre and a black streak, VHN100 ranges from 371–421, mean 395 kp/mm2 (15 indentations), roughly approximating to a Mohs hardness of 5. Dcalc = 8.308 g/cm3 for the ideal formula with Z = 2. In plane-polarised reflected light, the mineral is very slightly pleochroic from very light buff to slightly grey-green buff; is weakly bireflectant and has no internal reflections. Bireflectance is weak to moderate (higher in oil). Anisotropy is moderate and rotation tints vary from rose-brown to grey-green to pale bluish grey to dark steel-blue. Polysynthetic twinning is characteristic of the mineral. Reflectance spectra and colour values are tabulated. Very little variation was noted in eleven electron-microprobe analyses on five grains, the mean is: Ag 25.3, Cu 0.17, Pd 37.5, Se 36.4, total 99.37 wt.%. The empirical formula (on the basis of ∑M + Se = 9) is (Ag2.01Cu0.02)∑2.03 Pd3.02Se3.95, ideally Ag2Pd3Se4. Chrisstanleyite is monoclinic, a 6.350(6), b 10.387(4), c 5.683(3) Å β 114.90(5)°, space group P21/m (11) or P21(4). The five strongest X-ray powder-diffraction lines [d in Å (I)(hkl)] are: 2.742 (100) (–121), 2.688 (80) (–221), 2.367 (50) (140), 1.956 (100) (–321,150) and 1.829 (30) (–321, 042). The name is in honour of Dr Chris J. Stanley of The Natural History Museum in London. The mineral and its name have been approved by the Commission on New Minerals and Mineral Names of the International Mineralogical Association.

Macphersonite, a new mineral from Leadhills, Scotland, and Saint-Prix, France— a polymorph of leadhillite and susannite

1984 ◽  
Vol 48 (347) ◽  
pp. 277-282 ◽  
Author(s):  
A. Livingstone ◽  
H. Sarp
Keyword(s):  
Infrared Spectrum ◽  
Empirical Formula ◽  
New Mineral ◽  
Absorption Bands ◽  
X Ray ◽  
A Cell ◽  
Perfect Cleavage ◽  
Polysynthetic Twinning ◽  
Lead Hydroxyapatite ◽  
The Ideal

AbstractMacphersonite is white, resinous to adamantine, hardness (Mohs) 2½−3, density 6.50–6.55 gm/cm3 and possesses a perfect cleavage on {010}. Optically it is negative with 2Vα 35–36°, α = 1.87, β = 2.00 and γ = 2.01, α = b, γ = c, and γ = a, dispersion r > v. Polysynthetic twinning, with either coarse or fine lamellae, is common, as are contact twins. Crystals are orthorhombic, tabular on b with a 10.37, b 23.10 and c 9.25 Å, cell volume 2215.8 Å3 and space group Pcab; Z is 8 formula units. The seven strongest lines in the X-ray powder pattern are 3.274 (50) 052; 3.234 (100) 251; 2.654 (90) 351,203; 2.598 (30) 172, 400; 2.310 (30) 004, 371, 0.10.0; 2.182 (30) 263; and 2.033 (30) 234, 452, 154, 1.10.2. Electronprobe-microanalysis-determined chemistry leads to the empirical formula (Pb4.08, Cu0.10, Cd0.07)Σ4.25S0.90 C2.18O10.55(OH)1.58 which yields the ideal formula Pb4(SO4)(CO3)2(OH)2 and hence macphersonite is a polymorph of leadhillite and susannite. The infrared spectrum shows basic similarities to leadhillite and susannite spectra with additional diagnostic absorption bands. Macphersonite shows an identical thermogravimetric behaviour to that of leadhillite. It is associated, in varying combinations, with leadhillite, susannite, cerussite, caledonite, pyromorphite, scotlandite, galena, and the ‘lead hydroxyapatite’ of Temple (1955). The new mineral mimics leadhillite.

Growth twinning in phacolite

1987 ◽  
Vol 51 (361) ◽  
pp. 427-430 ◽  
Author(s):  
Mizuhiko Akizuki ◽  
Hiroshi Konno
Keyword(s):  
Nucleation Mechanism ◽  
Two Dimensional ◽  
The Face ◽  
Polysynthetic Twinning

AbstractPhacolite from Mitaki, Sendai City, Japan, has a core of penetration-twinned chabazite. The crystal has a convex (0001) face on which many twin individuals are produced by a two-dimensional nucleation mechanism, resulting in complicated twinning during growth. Both the r and the faces repeat finely during growth because of twinning, resulting in {112̄3} sectors with polysynthetic twinning. Finally, single structures nucleate on the crystal edges [211̄] and develop along the (112̄3) face, penetrating each other near the centre of the face.

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