scholarly journals Sieleckiite, a New Copper Aluminium Phosphate from Mt Oxide, Queensland, Australia

1988 ◽  
Vol 52 (367) ◽  
pp. 515-518 ◽  
Author(s):  
W. D. Birch ◽  
A. Pring
Keyword(s):  
Refractive Indices ◽  
South Australian Museum ◽  
Aluminium Phosphate ◽  
Type Specimens ◽  
Calculated Density ◽  
X Ray ◽  
Australian Museum ◽  
Simplified Formula ◽  
Measured Density ◽  
Mt Isa

AbstractSieleckiite is a new copper aluminium phosphate discovered at the Mt Oxide Copper Mine, 150 km north of Mt Isa, Queensland, Australia. It occurs with variscite, turquoise, libethenite and minor pseudomalachite in a fracture in a boulder of quartzite and shale. Sieleckiite forms deep sky blue to royal blue spheres up to 0.5 mm in diameter, made up of fibrous radiating crystals between 20 and 100 µm long and 1 to 2 µm wide. The mineral has a very pale blue streak and a pearly lustre on uneven fracture surfaces. Hardness is about 3 and the measured density is 3.02 g cm−3. The average of nine electron microprobe analyses gave CuO 32.39, Al2O3 26.57, P2O5 19.42%. Separate analyses gave H2O 18.1, CO2 1.6% (carbonate impurity). These data gave an empirical formula of Cu3.1Al4.0(PO4)2.1(OH)12.1.7H2O, calculated on the basis of 22 oxygen atoms. The simplified formula is Cu3Al4.0(PO4)2.1(OH)12.2H2O. The strongest lines in the X-ray powder diffraction pattern are {d(I)(hkl)}; 9.12(50)(100), 5.06(100)(101), 3.852(100)(111), 3.276(30)(2¯20), 2.827(50)(1¯02,102), 2.460(50)(3¯21). These data were indexed on a triclinic cell with a 9.41(8), b 7.56(5), c 5.95(6) Å, α 90.25(12)° β 91.27(12)° γ 104.02(7)° and a volume of 410.8(5) Å3. For Z = 1, the calculated density is 2.94 g cm−3. Optical properties could not be determined in full; the refractive indices are between 1.63 and 1.66, pleochroism is very weak from colourless to very pale blue.The mineral is named for the discoverer, Robert Sielecki (1958- ). Type specimens are preserved at the Museum of Victoria and the South Australian Museum. Sieleckiite was approved by the IMA Commission on New Minerals and Mineral Names prior to publication.

Steinmetzite, Zn2Fe3+(PO4)2(OH)·3H2O, a new mineral formed from alteration of phosphophyllite at the Hagendorf Süd pegmatite, Bavaria

2017 ◽  
Vol 81 (2) ◽  
pp. 329-338
Author(s):  
I. E. Grey ◽  
E. Keck ◽  
A. R. Kampf ◽  
W. G. Mumme ◽  
C. M. Macrae ◽  
...  
Keyword(s):  
Refractive Indices ◽  
New Mineral ◽  
Charge Balance ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Maximum Dimension ◽  
Calculated Density ◽  
X Ray ◽  
Cell Parameters ◽  
Simplified Formula

AbstractSteinmetzite, ideally Zn2Fe3+(PO4)2(OH)·3H2O, is a new mineral from the Hagendorf-Süd pegmatite, Hagendorf, Oberpfalz, Bavaria, Germany. Steinmetzite was found in a highly oxidized zone of the Cornelia mine at Hagendorf-Süd. It has formed by alteration of phosphophyllite, involving oxidation of the iron and some replacement of Zn by Fe. Steinmetzite lamellae co-exist with an amorphous Fe-rich phosphate in pseudomorphed phosphophyllite crystals. The lamellae are only a few μm thick and with maximum dimension ∼50 μm. The phosphophyllite pseudomorphs have a milky opaque appearance, often with a glazed yellow to orange weathering rind and with lengths ranging from sub-mm to 1 cm. Associated minerals are albite, apatite, chalcophanite, jahnsite, mitridatite, muscovite, quartz and wilhelmgümbelite.Goethite and cryptomelane are also abundant in the oxidized zone. The calculated density is 2.96 g cm–3. Steinmetzite is biaxial (–) with measured refractive indices α = 1.642(2), β = 1.659 (calc.), γ = 1.660(2) (white light). 2V(meas) = 27(1)°; orientation is Y ≈ b, X ^c ≈ 27°, with crystals flattened on {010} and elongated on [001]. Pleochroism shows shades of pale brown; Y > X ≈ Z. Electron microprobe analyses (average of seven crystals) with Fe reported as Fe2O3 and with H2O calculated from the structure gave ZnO 31.1, MnO 1.7, CaO 0.5, Fe2O3 21.9, Al2O3 0.3, P2O5 32.9, H2O 14.1 wt.%, total 102.5%. The empirical formula based on 2 P and 12 O, with all iron as ferric and OH–adjusted for charge balance is Zn1.65Fe1.193+ Mn0.112+Ca0.03Al0.023+(PO4)2(OH)1.21·2.79H2O. The simplified formula is Zn2Fe3+(PO4)2(OH)·3H2O.Steinmetzite is triclinic, P1̄, with unit-cell parameters: a = 10.438(2), b = 5.102(1), c = 10.546(2) Å, α = 91.37(2), β = 115.93(2) and γ = 94.20(2)°. V = 502.7(3) Å3, Z = 2. The strongest lines in the powder X-ray diffraction pattern are [dobs in Å (I) (hkl)] 9.313(65) (100), 5.077(38) (010), 4.726(47) (002), 4.657(100) (200), 3.365 (55) (3̄02), 3.071(54) (11̄2) and 2.735(48) (3̄1̄2). The structure is related to that of phosphophyllite.

Gajardoite, KCa0.5As3+4O6Cl2·5H2O, a new mineral related to lucabindiite and torrecillasite from the Torrecillas mine, Iquique Province, Chile

2016 ◽  
Vol 80 (7) ◽  
pp. 1265-1272 ◽  
Author(s):  
Anthony R. Kampf ◽  
Barbara P. Nash ◽  
Maurizio Dini ◽  
Arturo Molina A. Donoso
Keyword(s):  
Electron Microprobe ◽  
Room Temperature ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
Secondary Alteration ◽  
X Ray ◽  
Mohs Hardness ◽  
Measured Density ◽  
Irregular Cleavage

AbstractThe new mineral gajardoite (IMA2015-040), KCa0.5As3+4O6Cl2·5H2O, was found at the Torrecillas mine, Iquique Province, Chile, where it occurs as a secondary alteration phase in association with native arsenic, arsenolite,chongite, talmessite and torrecillasite. Gajardoite occurs as hexagonal plates up to ∼100 μm in diameter and 5 μm thick, in rosette-like subparallel intergrowths. Crystals are transparent, with vitreous lustre and white streak. The Mohs hardness is ∼1½, tenacity is brittleand fracture is irregular. Cleavage is perfect on {001}. The measured density is 2.64 g/cm3 and the calculated density is 2.676 g/cm3. Optically, gajardoite is uniaxial (–) with ω = 1.780(3) and ε = 1.570(5) (measured in white light). The mineral is very slowly soluble in H2O and slowly soluble in dilute HCl at room temperature. The empirical formula, determined from electron-microprobe analyses, is (K0.77Ca0.71Na0.05Mg0.05)∑1.58As4O11Cl1.96H9.62.Gajardoite is hexagonal, P6/mmm, a = 5.2558(8), c = 15.9666(18) Å, V = 381.96(13) Å3 and Z = 1. The eight strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 16.00(100)(001), 5.31(48)(003),3.466 (31)(103), 3.013(44)(104), 2.624(51)(006,110,111), 2.353(36)(113), 1.8647(21)(116,205) and 1.4605(17) (119,303,216). The structure, refined to R1 = 3.49% for 169 Fo > 4σF reflections, contains two types of layers. One layer of formulaKAs3+4O6Cl2 consists of two neutral As2O3 sheets, between which are K+ cations and on the outside of which are Cl– anions. This layer is topologically identical to a slice of the lucabindiite structureand similar to a slice of the torrecillasite structure. The second layer consists of an edge-sharing sheet of Ca(H2O)6 trigonal pyramids with isolated H2O groups centred in the hexagonal cavities in the sheet.

Khvorovite, Pb2+4Ca2[Si8B2(SiB)O28]F, a new hyalotekite-group mineral from the Darai-Pioz alkaline massif, Tajikistan: Description and crystal structure

2015 ◽  
Vol 79 (4) ◽  
pp. 949-963 ◽  
Author(s):  
Leonid A. Pautov ◽  
Atali A. Agakhanov ◽  
Elena Sokolova ◽  
Frank C. Hawthorne ◽  
Vladimir Y. Karpenko ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Refractive Indices ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
X Ray ◽  
Pyrochlore Group ◽  
Mohs Hardness ◽  
Ideal Composition ◽  
Alkaline Massif ◽  
Simplified Formula

AbstractKhvorovite, ideally Pb42+Ca2[Si8B2(SiB)O28]F, is a new borosilicate mineral of the hyalotekite group from the Darai-Pioz alkaline massif in the upper reaches of the Darai-Pioz river, Tajikistan. Khvorovite was found in a pectolite aggregate in silexites (quartz-rich rocks). The pectolite aggregate consists mainly of pectolite, quartz and fluorite, with minor aegirine, polylithionite, turkestanite and baratovite; accessory minerals are calcite, pyrochlore-group minerals, reedmergnerite, stillwellite-(Ce), pekovite, zeravshanite, senkevichite, sokolovaite, mendeleevite-(Ce), alamosite, orlovite, leucosphenite and several unknown Cs-silicates. Khvorovite occurs as irregular grains, rarely with square or rectangular sections up to 150 μm, and grain aggregates up to 0.5 mm. Khvorovite is colourless, rarely white, transparent with a white streak, has a vitreous lustre and does not fluoresce under ultraviolet light. Cleavage and parting were not observed. Mohs hardness is 5–5.5, and khvorovite is brittle with an uneven fracture. The measured and calculated densities are 3.96(2) and 3.968 g/cm3, respectively. Khvorovite is biaxial (+) with refractive indices (λ = 589 nm) α = 1.659(3), βcalc. = 1.671(2), γ = 1.676(3); 2Vmeas. = 64(3)°, medium dispersion: r < v. Khvorovite is triclinic, space group I1¯, a = 11.354(2), b = 10.960(2), c = 10.271(2) Å, α = 90.32(3), β = 90.00(3), γ = 90.00(3)°, V = 1278(1) Å3, Z = 2. The six strongest lines in the powder X-ray diffraction pattern [d (Å), I, (hkl)] are: 7.86, 100, (110); 7.65, 90, (101); 7.55, 90, (011); 3.81, 90, (202); 3.55, 90, (301); 2.934, 90, (312, 312). Chemical analysis by electron microprobe gave SiO2 36.98, B2O3 6.01, Y2O3 0.26, PbO 40.08, BaO 6.18, SrO 0.43, CaO 6.77, K2O 1.72, Na2O 0.41, F 0.88, O=F –0.37, sum 99.35 wt.%. The empirical formula based on 29 (O+F) a.p.f.u. is (Pb2.762+Ba0.62K0.56Na0.16)Σ4.10(Ca1.86Sr0.06Y0.04Na0.04)Σ2[Si8B2(Si1.46B0.65)Σ2.11O28](F0.71O0.29), Z = 2 , and the simplified formula is (Pb2+, Ba, K)4Ca2[Si8B2(Si,B)2O28]F. The crystal structure of khvorovite was refined to R1 = 2.89% based on 3680 observed reflections collected on a four-circle diffractometer with MoKα radiation. In the crystal structure of khvorovite, there are four [4]-coordinated Si sites occupied solely by Si with <Si–O>= 1.617 Å. The [4]-coordinated B site is occupied solely by B, with <B–O> = 1.478 Å. The [4]-coordinated T site is occupied by Si and B (Si1.46B0.54), with <T–O> = 1.605 Å; it ideally gives (SiB) a.p.f.u. The Si, B and T tetrahedra form an interrupted framework of ideal composition [Si8B2(SiB)O28]11–. The interstitial cations are Pb2+, Ba and K (minor Na) [A(11–22) sites] and Ca [M site]. The two A sites are each split into two subsites ∼0.5 Å apart and occupied by Pb2+ and Ba + K. The [8]-coordinated M site is occupied mainly by Ca, with minor Sr, Y and Na. Khvorovite is a Pb2+ analogue of hyalotekite, (Ba,Pb2+,K)4(Ca,Y)2[Si8(B,Be)2(Si,B)2O28]F and a Pb2+-, Ca-analogue of kapitsaite-(Y), (Ba,K)4(Y,Ca)2[Si8B2(B,Si)2O28]F. It is named after Pavel V. Khvorov (b. 1965), a Russian mineralogist, to honour his contribution to the study of the mineralogy of the Darai-Pioz massif.

Jentschite (TIPbAs2SbS6) – a new sulphosalt mineral from Lengenbach, Binntal (Switzerland)

1997 ◽  
Vol 61 (404) ◽  
pp. 131-137 ◽  
Author(s):  
Stefan Graeser ◽  
Andreas Edenharter
Keyword(s):  
Ordered Structure ◽  
X Ray Diffraction ◽  
Complete Structure ◽  
Calculated Density ◽  
X Ray ◽  
Dolomitic Rock ◽  
Structure Determinations ◽  
Mohs Hardness ◽  
Simplified Formula ◽  
Monoclinic Cell

AbstractJentschite, TlPbAs2SbS6, is a new sulphosalt mineral from the famous Lengenbach locality (Binntal, Switzerland). It was discovered in association with numerous other Tl-As-sulphosalts such as hutchinsonite, wallisite-hatchite, edenharterite, bernardite, abundant realgar and orpiment in small cavities in a dolomitic rock of Triassic age which forms part of the Penninic Monte-Leone-nappe. The first specimens consisted of extremely small polysynthetically twinned crystals; a later find yielded less complicated twinned crystals in sizes up to 2 mm length. Single crystal X-ray diffraction studies gave a monoclinic cell with a = 8.121(3), b = 23.969(9), c = 5.847(3) Å, β = 107.68(3)° V = 1084.3(5) Å3, Z = 4, space group P21/n. The strongest lines in the X-ray powder diagram are (dobs in Å, Iobs, hkl): 2.823 (100)(116), 3.587 (86)(221), 2.778 (84)(260), 3.998 (74)(060), 2.670 (58)(301), 3.816 (54)(210). Chemical composition (electron microprobe, mean of 15 analyses, wt.%) is: Tl 23.92, Pb 21.44, As 19.16, Sb 12.53, S 22.42, total 99.47 wt.% from which a simplified formula TlPbAs2Sb1S6 can be derived. This formula is very close to that of the (orthorhombic) mineral edenharterite TlPbAs3S6. From structural and chemical data it was interpreted as the ordered structure of an Sb-bearing relative of edenharterite, a postulation that meanwhile could be confirmed by the complete structure determinations of both, edenharterite and jentschite (Berlepsch, 1996). Jentschite occurs in prismatic crystals up to 2 mm length; it is opaque with a black metallic to submetallic luster, red translucent in thin fragments. Fracture is uneven to conchoidal, the mineral is extremely brittle, the cleavage along (01) is perfect; the streak is dark red (darker than that of edenharterite). Mohs hardness is 2–2½, according to a microhardness VHN (10 g load) of 38–51 kg/mm2. The calculated density yields Dcalc = 5.24 g/cm3.The name is for Franz Jentsch (1868–1908) from Binn, a local ‘Strahler’ and for several years head of an early Lengenbach syndicate that exploited the rare Lengenbach sulphosalt minerals at the beginning of this century.

scholarly journals On some Australian Termites of the Genera Drepanotermes, Hamitermes and Leucotermes

1922 ◽  
Vol 12 (4) ◽  
pp. 363-399 ◽  
Author(s):  
Gerald F. Hill
Keyword(s):  
Western Australia ◽  
Northern Territory ◽  
South Australian Museum ◽  
Large Collection ◽  
The South ◽  
Type Specimens ◽  
Australian Museum ◽  
The Past ◽  
Australian Continent

This paper is intended as the first of a series in which it is proposed to record the results of an examination of a large collection of termites from various parts of the Australian continent. The greater part of this collection has been gathered in the northern districts of the Northern Territory, and in North Queensland, but during the past year it has been considerably increased by the addition of numerous small collections received from correspondents in Victoria, Western Australia and South Queensland, and now contains individuals from over 800 colonies. Through the courtesy of the authorities of the South Australian Museum I have been able to examine a number of co-type specimens which have been of the greatest assistance in clearing up many doubtful identifications. In addition to these, I have been able to study many species from localities not represented in my own collection.

A study of the neotocite group

1978 ◽  
Vol 42 (322) ◽  
pp. 279-280 ◽  
Author(s):  
A. M. Clark ◽  
A. J. Easton ◽  
M. Mount
Keyword(s):  
Room Temperature ◽  
Original Description ◽  
Refractive Indices ◽  
Magnesium Perchlorate ◽  
Type Specimens ◽  
Subsequent Work ◽  
X Ray ◽  
Conchoidal Fracture ◽  
Infra Red ◽  
Iron Bearing

SynopsesAn examination has been carried out of ten specimens assigned to the group. These include metatype specimens of neotocite (Gestrikland, Sweden) and penwithite (Wheal Owles, Penwith, Cornwall) and topo-type specimens of stratopeïte (Pajsberg, Sweden), klipsteinite (Herborn, Dillenberg, Germany), and opsimose (specimen labelled klipsteinite, but from Klapperud, Dalecarlia, Sweden). The investigation arose out of the recent find of neotocite at the Geevor mine, Cornwall, close to the site of the type locality for penwithite.In the investigation klipsteinite has been confirmed as a mixture (Fisher, 188o), the dominant mineral in the mixture giving an X-ray pattern close to birnessite. Chemical analyses, refractive indices, and specific gravity determinations are given for the remainder in the miniprint section, p. M27 (Table I). They show that the group can be represented fairly closely by the formula (Mn, Fe)SiO3.H2O, but with significant carbonate present in each sample. CO2 has not generally been reported before in these minerals and the water content is lower than previous analyses, as a result of the precautions taken in drying the material before analysis (over magnesium perchlorate at room temperature).The specimens examined are all dark brown or black in appearance (often darkening on exposure to light) with a vitreous lustre and conchoidal fracture. The group should be regarded as poorly crystalline since all the specimens gave similar X-ray powder patterns with three very broad and diffuse lines around 3·5, 2·6, and 1·6 Å respectively (see Whelan and Goldich, 1961). After heating to 1000 °C all form braunite, with the exception of stratopeite, which gave an X-ray powder pattern closer to pyroxmangite. Hausmannite or spinel were also found associated with braunite in several specimens.The full text includes the results of differential thermal analysis and infra-red spectra from the samples.Of the names used in the group, opsimose (Beudant, 1832) was the first recorded, but in this and the subsequent work of Bahr (1850), it was associated with material much richer in manganese. Wittingite and neotocite (Nordenskiöld, 1849) were -named separately on account of the higher iron content of neotocite. Stratopeïte (Igelström, 1851) is a magnesium-bearing variety, while penwithite (Collins, 1878, 1879) was thought to have a different manganese valency state from wittingite.In view of its current widespread usage and the fact that neotocite was originally named for an iron-bearing manganese silicate it is proposed that neotocite be defined as the group of poorly crystalline manganese silicates with formulae close to (Mn, Fe)SiO3.H2O and Mn > Fe. With Fe > Mn the series grades into hisingerite. Limited substitution of MgO, Al2O3, and CO2 should be acceptable. Finally it has been proposed that the other names be discarded. The Commission on New Minerals and Mineral Names, IMA, has approved these proposals, but came to no firm conclusion as to whether the group name should be spelt ‘neotocite’ or as in the original description ‘neotokite’. Accordingly either are permissible.

Parkinsonite, (Pb,Mo, □)8O8Cl2, a new mineral from Merehead Quarry, Somerset

1994 ◽  
Vol 58 (390) ◽  
pp. 59-68 ◽  
Author(s):  
R. F. Symes ◽  
G. Cressey ◽  
A. J. Griddle ◽  
C. J. Stanley ◽  
J. G. Francis ◽  
...  
Keyword(s):  
Refractive Indices ◽  
New Mineral ◽  
Synthetic Material ◽  
Synthetic Sample ◽  
Calculated Density ◽  
X Ray ◽  
Usual Form ◽  
A Cell ◽  
The Difference ◽  
Crystalline Aggregates

AbstractParkinsonite, ideally (Pb,Mo,□)8O8Cl2, is a new mineral from the Merehead Quarry, Cranmore, Somerset, England. It occurs as compact clusters or patches of red to purplish red bladed crystals, which have an adamantine lustre and a perfect {001} cleavage and occupy fractures and cavities in carbonate vughs in veins of manganese and iron oxide and hydroxide minerals. Associated minerals are mendipite, diaboleite, chloroxiphite, wulfenite, cerussite and hydrocerussite. Discrete crystals were not found; intergrown crystalline aggregates are the usual form of occurrence. The maximum grain size is about 300 × 100 µm, but most grains are appreciably smaller. Parkinsonite was synthesized using high purity chemicals. The measured density of the synthetic material is 7.32 g/cm3; the calculated density is 7.39 g/cm3, the difference being due to minor impurity and slight porosity in the synthetic sample. Parkinsonite is translucent. Reflectance spectra were obtained in air and in oil. Refractive indices calculated from these (at 589 nm) are for Ro, 2.58, and Re', 2.42, i.e. uniaxial negative. VHN50 is 113–133 from which the calculated Mobs hardness is 2–2.5.X-ray studies show that parkinsonite is tetragonal with space group I4/mmm, I4̄2m, I4̄m2, I4/mm, or I422 and a 3.9922(3), c 22.514(2) Å. It has a cell volume of 358.82(5) Å3 with Z = 1. The strongest six lines of the X-ray powder diffraction pattern are [d in Å (I) (hkl)] 2.823, 2.813(100) (110,008); 5.63(85) (004); 2.251(33) (116, 0.0.10); 2.988(27) (105); 3.750(15) (006); 1.994(11) (200,118). Averaged electron microprobe analyses give the empirical formula Pb6.34Mo0.89□0.77O8.02Cl1.98 on the basis of 10 atoms [O + Cl]. The name is for Reginald F. D. Parkinson, mineral collector of Somerset, UK, who first found the mineral.

Schultenite from King County, Washington, USA; a second occurrence, and review

1985 ◽  
Vol 49 (350) ◽  
pp. 65-69 ◽  
Author(s):  
R. Falls ◽  
B. Cannon ◽  
J. A. Mandarino
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
King County ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Calculated Density ◽  
X Ray ◽  
Cell Parameters ◽  
Long Wave ◽  
Measured Density

AbstractSchultenite, PbHAsO4, known only from Tsumeb, Namibia, has been identified from a second occurrence: near North Bend, King County, Washington, USA. It occurs as euhedral crystals in a quartz-arsenopyrite-galena vein. It has a measured density of 6.07(3) g/cm3 and a calculated density of 6.079(4) g/cm3. The white to colourless crystals have a white streak, adamantine lustre, and fluoresce dull yellow under long wave ultraviolet light. Schultenite is monoclinic. Pa or P2/a; the unit cell parameters refined from the X-ray powder diffraction data are: a 5.827(3), b 6.743(3), c 4.847(3) Å, β 95.34(5)°; V 189.6(1) Å3; Z = 2; a:b:c = 0.8642:1:0.7188. The forms {010}, {001}, and {3̄22} were observed on the Washington schultenite crystals.

Vaughanite, TlHgSb4S7, a new mineral from Hemlo, Ontario, Canada

1989 ◽  
Vol 53 (369) ◽  
pp. 79-83 ◽  
Author(s):  
Donald C. Harris ◽  
Andrew C. Roberts ◽  
Alan J. Criddle
Keyword(s):  
Polarized Light ◽  
New Mineral ◽  
Drill Core ◽  
Unit Cell Parameters ◽  
Calculated Density ◽  
X Ray ◽  
Cell Parameters ◽  
Arterial Blood ◽  
Mohs Hardness ◽  
Simplified Formula

AbstractVaughanite, idealized formula T1HgSb4S7, is a very rare primary constituent of the Golden Giant orebody of the Hemlo gold deposit, Hemlo, Ontario, Canada. It was found in two polished sections from one drill core; as a 450 by 300 µm aggregate associated with pääkkönenite, stibnite, realgar, and native arsenic; and as a 40 µm anhedral grain associated with stibarsen and chalcostibite. Vaughanite is opaque with a metallic lustre and a black streak. No cleavage was observed but parting, produced by indentation, was detected as a series of weak parallel traces. It is brittle, with an even, occasionally arcuate, fracture. VHN25 is 100–115, mean 104. Mohs hardness (calc.) = 3−3½. In refected plane-polarized light in air the bireflectance is weak to moderate; the pleochroism is also weak, from a somewhat greenish grey to slightly darker bluish grey. Anisotropism is moderate to strong, with rotation tints in shades of green, yellow, purplish brown to brown. Reflectance spectra and colour values are tabulated. The colour in air is light grey. Internal reflections are rare but are arterial-blood-red on indentation fractures. X-ray studies have shown that vaughanite is triclinic with refined unit-cell parameters a 9.012 (3), b 13.223 (3), c 5.906 (2) Å, α 93.27 (3)°, β 95.05 (4)°, γ 109.16 (3)°, V 659.46 (80) Å3, a:b:c = 0.6815 : 1 : 0.4466 and Z = 2. The space group choices are P1 (1) or (2), diffraction aspect P*. The five strongest lines in the X-ray powder pattern [d in Å (l) (hkl)] are: 4.343 (30) (), 4.204 (100) (), 3.313 (60) (130), 2.749 (40) (, 131) and 2.315 (30) (, 122). The average of five electron microprobe analyses gave T1 18.3 (2), Hg 17.5 (2), Sb 43.4 (3), As 1.1 (1), S 20.5 (5), total 100.8 wt. %, corresponding, on the basis of total atoms = 13, to T10.98Hg0.95(Sb3.90As0.17)Σ4.07S7.00. The calculated density is 5.56 g/cm3 for the empirical formula and 5.62 g/cm3 for the simplified formula. The mineral is named for Professor David J. Vaughan.

Ranunculite, AlH(UO2)(PO4)(OH)3 · 4H2O, a new mineral

1979 ◽  
Vol 43 (327) ◽  
pp. 321-323 ◽  
Author(s):  
Michel Dellens ◽  
Paul Piret
Keyword(s):  
Chemical Analysis ◽  
Electron Microprobe ◽  
Powder Pattern ◽  
New Mineral ◽  
Calculated Density ◽  
X Ray ◽  
Mean Diameter ◽  
Measured Density

SummaryRanunculite occurs as gold-yellow nodules. Mean diameter = 0.3 mm. Optically biaxial negative, 2V (calc.) = 56°. γ =1.670, β = 1.664, and α = 1.643. Monoclinic, pseudo-orthorhombic with a = 11.1 Å, b = 17.7 Å, c = 18.0 Å, and β ⋍ 90°. Z = 14. Measured density = 3.4 g/cm3. Calculated density = 3.39 g/cm3. The strongest lines of the X-ray powder pattern are (d, hkl, I): 9.00, 002–020 (100), 3.133, 330 (80), 470, 202–220 (50), 2.978, 006–060 (40), and 1.850, 600 (40). Chemical analysis by electron microprobe: Al2O3 9.9%, UO3 54.5%, P2O5 13.2%, H2O by thermogravimetry 20.3%. Formula: AlH(UO2)(PO4)(OH)3 · 4H2O. Ranunculite occurs at Kobokobo, Kivu, Zaïre, in pegmatitic rocks. The name after the colour (ranunculus = buttercup).

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