Nolzeite, Na(Mn,□)2[Si3(B,Si)O9(OH)2]·2H2O, a new pyroxenoid mineral from Mont Saint-Hilaire, Québec, Canada

2017 ◽  
Vol 81 (1) ◽  
pp. 183-197 ◽  
Author(s):  
Monika M. M. Haring ◽  
Andrew M. McDonald
Keyword(s):  
Narrow Range ◽  
New Mineral ◽  
Chemical Analyses ◽  
Eudialyte Group ◽  
Sharp Band ◽  
Alkaline Conditions ◽  
Chain Silicate ◽  
A Chain ◽  
Low Pressures ◽  
Pale Green

AbstractNolzeite, Na(Mn,□)2[Si3(B,Si)O9(OH)2]·2H2O, is a new mineral found in altered sodalite syenite at the Poudrette quarry, La Vallée-du-Richelieu, Montérégie (formerly Rouville County), Québec, Canada. Crystals are colourless to pale green and are acicular with average dimensions of 5 μm × 8 μm × 55 μm. They occur as radiating to loose, randomly oriented groupings within vugs associated with aegirine, nepheline, sodalite, eudialyte-group minerals, analcime, natron, pyrrhotite, catapleiite, steedeite and the unidentified mineral, UK80. Nolzeite is non-pleochroic, biaxial, with nmin = 1.616(2) and nmax = 1.636(2) and has a positive elongation. The average of six chemical analyses gave the empirical formula: Na1.04(Mn1.69□0.24Fe0.05Ca0.02)∑=2.00(Si2.96S0.04)∑=3.00(B0.70Si0.30)∑=1.00O9(OH)2·2H2O based on 13 anions. The Raman spectrum shows six distinct bands occurring at ∼3600–3300 cm–1 and 1600–1500 cm–1 (O–H and H–O–H bending), 1300–1200 cm–1 (B–OH bending), 1030–800 cm–1 (Si–O–Si stretching) as well as 700–500 cm–1 and 400–50 cm–1 (Mn–O and Na–O bonding, respectively). The FTIR spectrum for nolzeite shows bands at ∼2800 –3600 cm–1(O–H) stretching, a moderately sharp band at 1631 cm –1(H–O–H) bending, strong, sharp bands at ∼650 –700 cm–1, ∼800 –840 cm–1, and ∼900–1100 cm–1(Si–O and B –O) bonds. Nolzeite is triclinic, crystallizing in space group P with a = 6.894(1), b = 7.632(2), c = 11.017(2) Å, α= 108.39(3), β= 99.03, γ = 103.05(3)°, V = 519.27 Å3, and Z = 2. The crystal structure was refined to R = 12.37% and wR2 = 31.07% for 1361 reflections (Fo > 4σFo). It is based on chains of tetrahedra with a periodicity of three (i.e. a dreier chain) consisting of three symmetrically independent SiO4 tetrahedra forming C-shaped clusters closed by BO2(OH)2 tetrahedra, producing single loop-branched dreier borosilicate chains. The chains are linked through shared corners to double chains of edge-sharing MnO5(OH) octahedra. Nolzeite is a chain silicate closely related to steedeite and members of the sérandite–pectolite series. Paragenetically, nolzeite is late-stage, probably forming under alkaline conditions and over a narrow range of low pressures and temperatures.

Fulbrightite, the Arsenate Analog of Sincosite

2020 ◽  
Vol 58 (5) ◽  
pp. 663-671
Author(s):  
Anthony R. Kampf ◽  
Mark A. Cooper ◽  
Barbara P. Nash ◽  
Joe Marty ◽  
Paul M. Adams ◽  
...  
Keyword(s):  
Secondary Phase ◽  
Thin Plates ◽  
New Mineral ◽  
Chemical Analyses ◽  
Triclinic Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Mohs Hardness ◽  
Pale Green ◽  
Light Green

ABSTRACT Fulbrightite (IMA2019–032), Ca(VO)2(AsO4)2·4H2O, is a new mineral from the Packrat mine, near Gateway, Mesa County, Colorado, USA, and from the Rovnost mine, Jáchymov, Czech Republic. It is a low-temperature secondary phase. The mineral most typically occurs in shades of light green and forms rosettes of roughly square (pseudotetragonal) plates. The streak is colorless to pale green and the luster is vitreous to pearly. The Mohs hardness is about 2½. Crystals are brittle, but slightly flexible in thin plates. Cleavages are (001) perfect, (100) and (010) excellent, (110) and fair. Fracture is stepped, irregular, and curved. The measured density is 3.12(2) g/cm3. The mineral is optically biaxial (–), α = 1.675(3), β = 1.718(3), and γ = 1.718(3) (white light); 2V ≈ 5°; orientation: X ≈ c; pleochroism: X colorless, Y and Z pale green (X < Y = Z). Electron-microprobe analyses gave the empirical formulae Ca0.99(V4+1.00O)2[(As5+0.98V5+0.02)O4]2·4(H2.005O) (Packrat mine) and (Ca1.02Fe0.01Ba0.01)Σ1.04(V4+O)1.96[(As5+0.99P0.01)O4]2·4.04H2O (Rovnost mine). X-ray powder diffraction (coupled with the chemical analyses) showed fulbrightite to be the arsenate analog of sincosite. The mineral is triclinic, space group P1, with cell parameters a = 6.434(8), b = 6.480(8), c = 6.718(8) Å, α = 107.90(6), β = 94.06(4), γ = 90.06(3)°, V = 265.8(6) Å3, and Z = 1. The Raman and infrared spectra of fulbrightite and sincosite are consistent with them being arsenate and phosphate analogs, respectively.

Sergevanite, Na15(Ca3Mn3)(Na2Fe)Zr3Si26O72(OH)3·H2O, a new eudialyte-group mineral from the Lovozero alkaline massif, Kola Peninsula

2020 ◽  
Vol 58 (4) ◽  
pp. 421-436 ◽  
Author(s):  
Nikita V. Chukanov ◽  
Sergey M. Aksenov ◽  
Igor V. Pekov ◽  
Dmitriy I. Belakovskiy ◽  
Svetlana A. Vozchikova ◽  
...  
Keyword(s):  
Kola Peninsula ◽  
Structural Data ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
Eudialyte Group ◽  
Group Mineral ◽  
X Ray ◽  
Mohs Hardness ◽  
Alkaline Massif

ABSTRACT The new eudialyte-group mineral sergevanite, ideally Na15(Ca3Mn3)(Na2Fe)Zr3Si26O72(OH)3·H2O, was discovered in highly agpaitic foyaite from the Karnasurt Mountain, Lovozero alkaline massif, Kola Peninsula, Russia. The associated minerals are microcline, albite, nepheline, arfvedsonite, aegirine, lamprophyllite, fluorapatite, steenstrupine-(Ce), ilmenite, and sphalerite. Sergevanite forms yellow to orange-yellow anhedral grains up to 1.5 mm across and the outer zones of some grains of associated eudialyte. Its luster is vitreous, and the streak is white. No cleavage is observed. The Mohs' hardness is 5. Density measured by equilibration in heavy liquids is 2.90(1) g/cm3. Calculated density is equal to 2.906 g/cm3. Sergevanite is nonpleochroic, optically uniaxial, positive, with ω = 1.604(2) and ε = 1.607(2) (λ = 589 nm). The infrared spectrum is given. The chemical composition of sergevanite is (wt.%; electron microprobe, H2O determined by HCN analysis): Na2O 13.69, K2O 1.40, CaO 7.66, La2O3 0.90, Ce2O3 1.41, Pr2O3 0.33, Nd2O3 0.64, Sm2O3 0.14, MnO 4.15, FeO 1.34, TiO2 1.19, ZrO2 10.67, HfO2 0.29, Nb2O5 1.63, SiO2 49.61, SO3 0.77, Cl 0.23, H2O 4.22, –O=Cl –0.05, total 100.22. The empirical formula (based on 25.5 Si atoms pfu, in accordance with structural data) is H14.46Na13.64K0.92Ca4.22Ce0.27La0.17Nd0.12Pr0.06Sm0.02Mn1.81Fe2+0.58Ti0.46Zr2.67Hf0.04Nb0.38Si25.5S0.30Cl0.20O81.35. The crystal structure was determined using single-crystal X-ray diffraction data. The new mineral is trigonal, space group R3, with a = 14.2179(1) Å, c = 30.3492(3) Å, V = 5313.11(7) Å3, and Z = 3. In the structure of sergevanite, Ca and Mn are ordered in the six-membered ring of octahedra (at the sites M11 and M12), and Na dominates over Fe2+ at the M2 site. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 7.12 (70) (110), 5.711 (43) (202), 4.321 (72) (205), 3.806 (39) (033), 3.551 (39) (220, 027), 3.398 (39) (313), 2.978 (95) (), 2.855 (100) (404). Sergevanite is named after the Sergevan' River, which is near the discovery locality.

On Fermorite, a new arsenate and Phosphate of lime and strontia, and Tilasite, from the manganese-ore deposits of India

1911 ◽  
Vol 16 (74) ◽  
pp. 84-96 ◽  
Author(s):  
G. F. Herbert Smith ◽  
G. T. Prior
Keyword(s):  
Central India ◽  
Ore Deposits ◽  
The Other ◽  
New Mineral ◽  
Manganese Ore ◽  
Manganese Ores ◽  
Pale Green

Analyses of Indian manganese-ores generally show the presence of small amounts of arsenic. The form in which this constituent occurs was discovered by Dr. L. Leigh Fermor in the course of his investigations of these well-known deposits. At two different localities crystalline arsenates were found. One of these occurrences is at the Sitapar deposit in the Chhindwara district, Central Provinces. The pinkish-white to white arsenate found there is the new mineral to which we have given the name fermorite. The other locality at which an arsenate was found is Kajlidongri, Jhabua State, Central India. The pale-green arsenate, somewhat resembling apatite in appearance, which occurs at this locality has been found by us to be identical with the tilasite from Sweden described by Sjögren.

scholarly journals The oxidation of phosphine at low pressures

1929 ◽  
Vol 125 (797) ◽  
pp. 294-308 ◽  
Keyword(s):  
Energy Content ◽  
Stable Condition ◽  
High Energy ◽  
Gaseous Reaction ◽  
Molecular Collision ◽  
Active Chemical ◽  
Recent Developments ◽  
Collision Processes ◽  
A Chain ◽  
Low Pressures

In the recent developments of chemical kinetics there have been many indications of a type of reaction known as a chain reaction, in which each act of transformation gives rise to a product which, on account of its active chemical nature or high energy content, causes further molecules to be transformed without special activation. Under certain conditions the chain may "branch," and the number of centers from which reaction proceeds increases indefinitely unless the chains are broken. In a gaseous reaction there may be a definite concentration at which the rate of initiation of chains just begins to exceed the rate at which they are broken. At this point a stable condition ceases to be possible. However slow the reaction may be on one side of the limiting concentration, on the other side its rate increases continuously with time till explosion results. The acceleration may require an imperceptible fraction of a second only, since the time scale on which molecular collision processes occur is a very minute one. The remarkable phenomenon to which this gives rise, namely an abrupt transition from negligibly slow reaction to explosion, is exemplified in the union of oxygen with phosphorus vapour and with sulphur vapour at low pressure, and in the combination of hydrogen and oxygen under certain conditions. The present paper deals with a similar phenomenon in the oxidation of phosphine.

Pauladamsite, Cu4(SeO3)(SO4)(OH)4·2H2O, a new mineral from the Santa Rosa mine, Darwin district, California, USA

2016 ◽  
Vol 80 (6) ◽  
pp. 949-958 ◽  
Author(s):  
A. R. Kampf ◽  
S. J. Mills ◽  
B. P. Nash
Keyword(s):  
New Mineral ◽  
X Ray Diffraction ◽  
Secondary Oxidation ◽  
Calculated Density ◽  
Teller Distortion ◽  
Jahn Teller ◽  
Perfect Cleavage ◽  
Mohs Hardness ◽  
Jahn Teller Distortion ◽  
Pale Green

AbstractPauladamsite (IMA2015-005), Cu4(SeO3)(SO4)(OH)4·2H2O, is a new mineral from the Santa Rosa mine, Darwin district, Inyo County, California, USA, where it occurs as a secondary oxidation-zone mineral in association with brochantite, chalcanthite, gypsum, ktenasite, mimetite, schulenbergite and smithsonite on limonitic gossan. Pauladamsite forms green, multiply twinned blades up to 0.5 mm long grouped in radial sprays. The streak is pale green. Crystals are transparent and have vitreous to silky lustre. The Mohs hardness is ∼2, the tenacity is brittle, the fracture is irregular and crystals exhibit one perfect cleavage on [001]. The calculated density is 3.535 g/cm3. Electron microprobe analyses provided: CuO 48.96, ZnO 3.56, SeO2 18.82, SO3 13.90, H2O 13.29 (calc.), total 98.53 wt.%. The empirical formula (based on 13 O apfu) is: (Cu3.55Zn0.25)∑3.80Se0.98SO13H8.50. Pauladamsite is triclinic, P1, a = 6.0742(7), b = 8.4147(11), c = 10.7798 (15) Å, α = 103.665(7), β = 95.224(7), γ = 90.004(6)°, V = 533.03(12) Å3 and Z = 2. The eight strongest lines in the powder X-ray diffraction pattern are [dobs in Å(I)(hkl)]: 10.5(46)(011); 3.245(100)(001); 5.81(50)(011); 2.743(49)(112); 3.994(67)(012); 3.431(23)(1̄12,1̄2̄1,1̄20); 2.692(57)(03̄2,1̄22,2̄1̄2); and 2.485(39)(21̄2,1̄3̄2,02̄4). The structure of pauladamsite (R1 = 10.6% for 2086 Fo > 4σF) contains Cu2+O6 octahedra, SO4 tetrahedra and Se4+O3 pyramids. There are four different CuO6 octahedra, each of which exhibits typical Jahn-Teller distortion, with four short equatorial Cu–O bonds and two much longer apical Cu–O bonds. The CuO6 octahedra share edges to form five-octahedra-wide bands extending along [100]. Adjacent bands are connected in the [011̄] direction by bridging SO4 tetrahedra and in the [011] direction by bridging Se4+O3 pyramids, thereby forming a framework.

Lussierite, a new sodium uranyl sulfate mineral with bidentate UO7–SO4linkage from the Blue Lizard mine, San Juan County, Utah, USA

2019 ◽  
Vol 83 (6) ◽  
pp. 799-808 ◽  
Author(s):  
Anthony R. Kampf ◽  
Travis A. Olds ◽  
Jakub Plášil ◽  
Barbara P. Nash ◽  
Joe Marty
Keyword(s):  
Pentagonal Bipyramid ◽  
New Mineral ◽  
San Juan ◽  
Charge Balance ◽  
Uranyl Sulfate ◽  
Wavelength Dispersive Spectroscopy ◽  
X Ray ◽  
Mohs Hardness ◽  
San Juan County ◽  
Pale Green

AbstractThe new mineral lussierite (IMA2018-101), Na10[(UO2)(SO4)4](SO4)2(H2O)3, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as pale green–yellow prisms or blades in a secondary assemblage with belakovskiite, ferrinatrite, halite, ivsite, metavoltine and thénardite. The streak is white and the fluorescence is bright cyan under 365 nm ultraviolet light. Crystals are transparent with vitreous lustre. The tenacity is brittle, the Mohs hardness is 2½, the fracture is irregular and no cleavage was observed. The mineral is easily soluble in H2O and has a measured density of 2.87(2) g cm–3. Lussierite is optically biaxial (+), with α = 1.493(1), β = 1.505(1) and γ = 1.518(1) (white light); 2Vmeas.= 88(1)°; dispersion isr>v, moderate; pleochroism:X= colourless,YandZ= green yellow (X<Y≈Z); optical orientation:X=b,Z∧a= 44° in obtuse β. Electron microprobe analyses (wavelength-dispersive spectroscopy mode) provided Na10(U0.99O2)(S1.00O4)6·3H2O (+0.06 H for charge balance). The five strongest X-ray powder diffraction lines are [dobsÅ(I)(hkl)]: 6.69(95)($\bar{1}$11,130), 4.814(100)(150,002,060), 3.461(83)(171,$\bar{2}$02), 2.955(81)(113,330) and 2.882(74)($\bar{1}$91,311,191,0·10·0). Lussierite is monoclinic,Cc,a= 9.3134(4),b= 28.7501(11),c= 9.6346(7) Å, β = 93.442(7)°,V= 2575.1(2) Å3andZ= 4. The structure (R1= 0.0298 for 5202I> 2σI) contains a [(UO2)(SO4)4]6–uranyl sulfate cluster in which one SO4tetrahedron shares an edge (bidentate linkage) with the UO7pentagonal bipyramid. The uranyl sulfate clusters occur in layers and are linked through a complex network of bonds involving Na+cations, isolated SO4tetrahedra and isolated H2O groups.

New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. I. Yurmarinite, Na7(Fe3+,Mg,Cu)4(AsO4)6

2014 ◽  
Vol 78 (4) ◽  
pp. 905-917 ◽  
Author(s):  
I. V. Pekov ◽  
N. V. Zubkova ◽  
V. O. Yapaskurt ◽  
D. I. Belakovskiy ◽  
I. S. Lykova ◽  
...  
Keyword(s):  
Scoria Cone ◽  
Ore Deposits ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
X Ray ◽  
Tolbachik Volcano ◽  
Mohs Hardness ◽  
Heteropolyhedral Framework ◽  
Pale Green

AbstractA new mineral, yurmarinite, Na7(Fe3+,Mg,Cu)4(AsO4)6, occurs in sublimates of the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with hatertite, bradaczekite, johillerite, hematite, tenorite, tilasite and aphthitalite. Yurmarinite occurs as well-shaped, equant crystals up to 0.3 mm in size, their clusters up to 0.5 mm and thin, interrupted crystal crusts up to 3 mm × 3 mm on volcanic scoria. Crystal forms are {101}, {011}, {100}, {110} and {001}. Yurmarinite is transparent, pale green or pale yellowish green to colourless. The lustre is vitreous and the mineral is brittle. The Mohs hardness is ∼4½. One direction of imperfect cleavage was observed, the fracture is uneven. D(calc.) is 4.00 g cm−3. Yurmarinite is optically uniaxial (−), ω = 1.748(5), ε = 1.720(3). The Raman spectrum is given. The chemical composition (wt.%, electron microprobe data) is Na2O 16.85, K2O 0.97, CaO 1.28, MgO 2.33, MnO 0.05, CuO 3.17, ZnO 0.97, Al2O3 0.99, Fe2O3 16.44, TiO2 0.06, P2O5 0.12, V2O5 0.08, As2O5 56.68, total 99.89. The empirical formula, calculated on the basis of 24 O atoms per formula unit, is (Na6.55Ca0.28K0.22)S7.05(Fe2.483+Mg0.70Cu0.48Al0.23Zn0.14Ti0.01Mn0.01)S4.05(As5.94P0.02V0.01)S5.97O24. Yurmarinite is rhombohedral, Rc, a = 13.7444(2), c = 18.3077(3) Å, V = 2995.13(8) Å3, Z = 6. The strongest reflections in the X-ray powder pattern [d, Å (I)(hkl)] are: 7.28(45)(012); 4.375(33)(211); 3.440(35)(220); 3.217(36)(131,214); 2.999(30)(223); 2.841(100)(125); 2.598(43)(410). The crystal structure was solved from single-crystal X-ray diffraction data to R = 0.0230. The structure is based on a 3D heteropolyhedral framework formed by M4O18 clusters (M = Fe3+ > Mg,Cu) linked with AsO4 tetrahedra. Sodium atoms occupy two octahedrally coordinated sites in the voids of the framework. In terms of structure, yurmarinite is unique among minerals but isotypic with several synthetic compounds with the general formula (Na7–x☐x)(M3+x3+M1–x2+)(T5+O4)2 in which T = As or P, M3+ = Fe or Al, M2+ = Fe and 0 ≤ x ≤ 1. The mineral is named in honour of the Russian mineralogist, petrologist and specialist in studies of ore deposits, Professor Yuriy B. Marin (b. 1939). The paper also contains a description of the Arsenathaya fumarole and an overview of arsenate minerals formed in volcanic exhalations.

scholarly journals Fluoro-aluminoleakeite, NaNa2(Mg2Al2Li)Si8O22F2, a new mineral of the amphibole group from Norra Kärr, Sweden: description and crystal structure

2009 ◽  
Vol 73 (5) ◽  
pp. 817-824 ◽  
Author(s):  
R. Oberti ◽  
F. Cámaraite ◽  
F. C. Hawthorne ◽  
N. A. Ball
Keyword(s):  
Crystal Structure ◽  
Structure Refinement ◽  
Polarized Light ◽  
Crystal Structure Analysis ◽  
New Mineral ◽  
Monoclinic Space Group ◽  
Calculated Density ◽  
Greenish Blue ◽  
Dark Green ◽  
Pale Green

AbstractFluoro-aluminoleakeite, ideally , is a new mineral of the amphibole group from Norra Kärr, Sweden (IMA-CNMMNC 2009-012). It occurs in a proterozoic alkaline intrusion that mainly comprises a fine-grained schistose agpaitic nepheline-syenite (grennaite). Fluoro- aluminoleakeite occurs as isolated prismatic crystals 0.10–2 mm long in a syenitic matrix. Crystals are light greenish-blue with a greenish-blue streak. It is brittle, has a Mohs hardness of 6 and a splintery fracture; it is non-fluorescent with perfect {110} cleavage, no observable parting, and has a calculated density of 3.14 g cm–3. In plane-polarized light, it is pleochroic, X = pale green, Y = dark green, Z = pale green; X ^ a = 62.9° (in β obtuse), Y || b. Fluoro-aluminoleakeite is biaxial negative, α = 1.632(1), β = 1.638(1), γ = 1.643(1); 2Vobs. = 98.0(4)°, 2Vcalc. = 95.5°.MFluoro-aluminoleakeite is monoclinic, space group C2/m, a = 9.7043(5) Å, b = 17.7341(8) Å, c = 5.2833(3) Å, β = 104.067(4)°, V = 882.0(2) Å3, Z = 2. The eight strongest X-ray diffraction lines in the powder-diffraction pattern are [d in Å, (I), (hkl)]: 2.687, (100), (31, 151); 4.435, (80), (021, 040); 3.377, (80), (131); 2.527, (60), (02); 8.342, (50), (110); 3.096, (40), (310); 2.259, (40), (71, 12) and 2.557, (30), (002, 061). Analysis, by a combination of electron microprobe and crystal-structure refinement, gives SiO2 58.61, Al2O3 7.06, TiO2 0.32, FeO 3.27, Fe2O3 6.05, MgO 8.61, MnO 0.73, ZnO 0.43, CaO 0.05, Na2O 9.90, K2O 2.43, Li2O 1.62, F 3.37, H2Ocalc. 0.50, sum 101.08 wt.%. The formula unit, calculated on the basis of 24 (O,OH,F,Cl) p.f.u. with (OH) + F = 2 a.p.f.u., is A(Na0.65 O22W(F1.47OH0.53)Σ=2.00. Crystal-structure analysis shows CLi to be completely ordered at the M(3) site, and provided reliable site populations. Fluoro-aluminoleakeite is related to the end-member leakeite, , by the substitutions CFe3+ → CAl and WF → W(OH).

Kapellasite, Cu3Zn(OH)6CI2, a new mineral from Lavrion, Greece, and its crystal structure

2006 ◽  
Vol 70 (3) ◽  
pp. 329-340 ◽  
Author(s):  
W. Krause ◽  
H.-J. Bernhardt ◽  
R.S.W. Braithwaite ◽  
U. Kolitsch ◽  
R. Pritchard
Keyword(s):  
Crystal Structure ◽  
Electron Microprobe ◽  
Empirical Formula ◽  
New Mineral ◽  
Crystal Data ◽  
Secondary Mineral ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Pale Green ◽  
Light Green

AbstractKapellasite, Cu3Zn(OH)6Cl2, is a new secondary mineral from the Sounion No. 19 mine, Kamariza, Lavrion, Greece. It is a polymorph of herbertsmithite. Kapellasite forms crusts and small aggregates up to 0.5 mm, composed of bladed or needle-like indistinct crystals up to 0.2 mm long. The colour is green-blue, the streak is light green-blue. There is a good cleavage parallel to ﹛0001﹜. Kapellasite is uniaxial negative, ω = 1.80(1), ε = 1.76(1); pleochroism is distinct, with E = pale green, O = green-blue. Dmeas = 3.55(10) g/cm3; Dcalc. = 3.62 g/cm3. Electron microprobe analyses of the type material gave CuO 58.86, ZnO 13.92, NiO 0.03, CoO 0.03, Fe2O3 0.04, Cl 16.70, H2O (calc.) 12.22, total 101.80, less O = Cl 3.77, total 98.03 wt.%. The empirical formula is (Cu3.24Zn0.75)Σ3.99(OH)5.94Cl2.06, based on 8 anions. The five strongest XRD lines are [d in Å (I/I0, hkl)] 5.730 (100, 001), 2.865 (11, 002), 2.730 (4, 200), 2.464 (9, 021/201), 1.976 (5, 022/202). Kapellasite is trigonal, space group Pml, unit-cell parameters (from single-crystal data) a = 6.300(1), c = 5.733(1) Å, V= 197.06(6) Å3, Z = 1. The crystal structure of kapellasite is based on brucite-like sheets parallel to (0001), built from edge-sharing distorted M(OH,Cl)6 (M = Cu, Zn) octahedra. The sheets stack directly on each other (…AAA… stacking). Bonding between adjacent sheets is only due to weak hydrogen and O…C1 bonds. The name is in honour of Christo Kapellas (1938–2004), collector and mineral dealer from Kamariza, Lavrion, Greece.

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