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Tomiolloite (IMA2021-019) is a new aluminum tellurite sulfite-sulfate mineral discovered at the Bambolla mine, Moctezuma, Sonora, Mexico, a well-known tellurium (Te) mineral locality. Tomiolloite forms roughly spherical clusters of crystals comprised of very thin, needle-like crystals (1 μm diameter, ~40 μm length) around a core of small, stubbier, broken crystals. Tomiolloite is generally found growing on tellurite or quartz. The strongest powder X‑ray diffraction lines are [dobs Å (Iobs) (hkl)]: 11.667 (89) (100), 8.240 (38) (101), 4.107 (29) (202,211,121), 3.223 (100) (203,302,130), and 2.905 (37) (213,123,222,400). The empirical formula of tomiolloite, as determined by electron microprobe analysis, is (Al10.64Te61.01+ Fe30.31+ Zn0.04)Σ12(Te45.00+ Pb0.02)Σ5.02(S40.49+ S60.49+ Si0.02)Σ1.00O21.53[(OH)20.86Cl0.11]Σ20.97, which is simplified to the ideal formula Al12(Te4+O3)5[(SO3)0.5(SO4)0.5](OH)24. Significant Te6+ substitution for Al3+ is observed in tomiolloite, verified by X‑ray photoelectron spectroscopy and crystal-structure analysis. The structure of tomiolloite was determined using synchrotron single-crystal X‑ray diffraction, showing that tomiolloite is hexagonal and crystallizes in the space-group P63/m, with the unit-cell parameters a = 13.3360(19) Å, c = 11.604(2) Å, V = 1787.3(6) Å3, and Z = 2. Tomiolloite has a unique microporous framework structure, which bears a slight similarity to that of zemannite, but it has a much larger cavity diameter (8.85 Å). The framework is built from edge-sharing Mφ6 octahedra (M = Al3+ and Te6+), Te4+O3 trigonal pyramids, and Te4+O4 disphenoids. Mφ6 octahedra edge-share to form crankshaft-shaped chains along c, with Te4+On polyhedra filling notches in the crankshafts and providing linkages between adjacent chains. The framework has an overall positive charge, which is balanced by the presence of both sulfite (SO32−) trigonal pyramids and sulfate (SO42−) tetrahedra in the channels. [ABSTRACT FROM AUTHOR]

The new mineral flaggite (IMA2021-044), Pb4Cu2+4Te6+2(SO4)2O11(OH)2(H2O), occurs at the Grand Central mine in the Tombstone district, Cochise County, Arizona, USA, in cavities in quartz matrix in association with alunite, backite, cerussite, jarosite and rodalquilarite. Flaggite crystals are lime-green to yellow-green tablets, up to 0.5 mm across. The mineral has a very pale green streak and adamantine lustre. It is brittle with irregular fracture and a Mohs hardness of ~3. It has one excellent cleavage on {010}. The calculated density is 6.137 g cm–3. Optically, the mineral is biaxial (+) with α = 1.95(1), β = 1.96(1), γ = 2.00(1) (white light); 2V = 54(2)°; pleochroism: X green, Y light yellow green, Z nearly colourless; X > Y > Z. The Raman spectrum exhibits bands consistent with TeO6 and SO4. Electron microprobe analysis provided the empirical formula Pb3.88Cu2+3.89Te6+2.08(SO4)2O11(OH)2(H2O) (–0.03 H). Flaggite is triclinic, P1, a = 9.5610(2), b = 9.9755(2), c = 10.4449(3) Å, α = 74.884(1), β = 89.994(1), γ = 78.219(1)°, V = 939.97(4) Å3 and Z = 2. The structure of flaggite (R1 = 0.0342 for 5936 I > 2σI) contains hexagonal-close-packed, stair-step-like layers comprising TeO6 octahedra and Jahn-Teller distorted CuO6 octahedra. The layers in the structure of flaggite are very similar to those in bairdite, timroseite and paratimroseite. [ABSTRACT FROM AUTHOR]

An unusually diverse array of 25 secondary Te oxysalt minerals has been documented from Otto Mountain, California, and 18 of these from the Bird Nest drift sublocality. A paragenetic sequence for these minerals is proposed, using observed overgrowth relationships plus spatial association data and data from other localities. Apart from Te and O, the components Pb, Cu and H are essential in the majority of the minerals. The atomic Cu/Te ratio decreases through the paragenetic sequence. This, and the occurrence of minerals with additional components such as Cl-, CO2-3 , SO2-4 and Fe3+ at an intermediate stage, suggests nonmonotonic evolution of the parent fluids, reflecting differing access to or spatial distribution of various components. For the minerals with known crystal structures, two alternative 'structural units' were identified, one consisting only of the Te4+ or Te6+ oxyanion, while the other also included small, strongly-bound cations such as Cu2+. The degree of polymerization for the Te oxyanion correlated with the paragenetic sequence: the monomeric tellurate anions of early minerals were replaced progressively by dimers, chains and sheet structures, which may relate to a decreasing abundance of the 'network modifying' Cu2+ cation, analogous to Bowen's discontinuous reaction series in igneous rock-forming silicates. No relationship was seen between paragenetic order and the larger type of structural unit, or structural complexity as defined by information content. This contrasts with results in the literature for evaporite sulfates and pegmatite phosphates. While structure-paragenesis relationships may be widespread, the exact nature of such relationships may be different for different chemical systems and different paragenetic environments. [ABSTRACT FROM AUTHOR]

The crystal structure of burckhardite from the type locality, Moctezuma, Sonora, Mexico, has been refined to R1= 0.0362 and wR2= 0.0370 for 215 reflections with I> 2σ(I). Burckhardtite is trigonal, space group P31m, with the unit-cell parameters a= 5.2566(5) Å, c= 13.0221(10) Å, V= 311.62(5) Å3and Z= 1 for the ideal formula unit Pb2(Fe3䷮)[AlSi3O8]O6. There is no long-range order of (Fe3, Te6) or (Al3, Si4). New microprobe data were used to estimate site scattering factors, and Raman spectroscopic data showed no evidence of O–H stretching bands. Burckhardtite is not closely related to the micas, as supposed previously, but is a double-sheet silicate in which the aluminosilicate anion resembles that of minerals such as cymrite and kampfite. The [(Fe3䷮)O6]3–part of the structure is not bonded directly to the aluminosilicate layer, but forms a discrete anionic phyllotellurate layer that alternates with the [AlSi3O8]–double sheets. Similar phyllotellurate layers are known from several synthetic phases. In burckhardtite, Pb2熫抢 intercalate between phyllosilicate and phyllotellurate layers, forming a Pb2[FeTeO6] module that is topologically similar to a slab of the structure of rosiaite, Pb[Sb2O6]. The crystal symmetry, structure, classification as a double-sheet silicate and chemical formula, including the determination of the 6 valence of Te and absence of essential H2O, are all new findings for the mineral. [ABSTRACT FROM AUTHOR]

Eckhardite, (Ca, Pb)Cu2+Te6+O5(H2O), is a new tellurate mineral from Otto Mountain near Baker, California, U.S.A. It occurs in vugs in quartz in association with Br-rich chlorargyrite, gold, housleyite, khinite, markcooperite, and ottoite. It is interpreted as having formed from the partial oxidation of primary sulfides and tellurides during or following brecciation of quartz veins. Eckhardite is mono-clinic, space group P21/n, with unit-cell dimensions a = 8.1606(8), b = 5.3076(6), c = 11.4412(15) Å, β = 101.549(7)°, V= 485.52(10) ų, and Z = 4. It forms as needles or blades up to about 150 x 15 x 5 µm in size, typically in radial or sub-radial aggregates, but also as isolated needles. The color is light bluish green and the streak is very pale bluish green. Crystals are transparent with vitreous to subadamantine luster. The Mohs hardness is estimated at between 2 and 3. Eckhardite is brittle with an irregular fracture and one likely (but not observed) cleavage on {101}. The calculated density based on the empirical formula is 4.644 g/cm³. The mineral is biaxial (-), with indices of refraction of a = 1. 770 (calc), β = 1.860 (calc), and β = 1.895(5). The measured 2V is 61.2(5)°, dispersion is r < v, perceptible and the optical orientation is Z = b; X ≈ [101]. The pleochroism is: Z (light blue green) < Y (very pale blue green) 4sF) consists of stair-step-like octahedral layers of Te6+O6 and Cu2+O6 octahedra parallel to {101}, which are linked in the [101] direction by bonds to interlayer Ca atoms. The structure can be described as a stacking of stepped HCP layers alternating with chains of CaO7 polyhedra. The structures of bairdite, timroseite, and paratimroseite also contain stair-step-like HCP polyhedral layers. [ABSTRACT FROM AUTHOR]

Bairdite, Pb2Cu42+Te26+O10(OH)2(SO4)(H2O), is a new tellurate-sulfate from Otto Mountain near Baker, California, U.S.A. It occurs in vugs in quartz associated with khinite, cerussite, goethite, and hematite. It is interpreted as having formed from the partial oxidation of primary sulfides and tellurides during or following brecciation of quartz veins. Bairdite is monoclinic, space group P21/c, with unit-cell dimensions a = 14.3126(10), b = 5.2267(3), c = 9.4878(5) Å, b = 106.815(7)°, V = 679.41(7) Å3, and Z = 2. Bairdite occurs as diamond-shaped tabular crystals up to about 250 mm long and 5 mm thick, in subparallel and fan-shaped aggregates. The color is lime green, the streak is pale lime green, and the luster is adamantine. The Mohs hardness is estimated at between 2 and 3. Bairdite is brittle with an irregular fracture and one perfect cleavage on {100}. The calculated density based on the empirical formula is 6.062 g/cm3. Bairdite is biaxial (+), with calculated indices of refraction of a = 1.953, b = 1.966, and g = 2.039. The measured 2V is 47(2)°, dispersion is r < v, strong and the optical orientation is Y = b; Z ^ a = 34° in obtuse angle b. The pleochroism is strong: Z (pale green) <<< X (green) < Y (green). Electron microprobe analyses (average of 4) provided: PbO 34.22, CaO 0.06, CuO 23.80, TeO3 26.34, SO3 5.74, H2O 2.81 (structure), total 92.97 wt%. The empirical formula (based on 17 O atoms pfu) is: Pb2.05Ca0.01Cu2+3.99Te6+2.00S0.96O17.00H4.16. The eight strongest powder X-ray diffraction lines are [dobs in Å (hkl) I]: 4.77 (110,102) 50, 4.522 (002,011,111) 66, 3.48 (multiple) 62, 2.999 (311,411) 97, 2.701 (502,113,213) 79, 2.614 (013,020) 100, 1.727 (multiple) 65, and 1.509 (911,033,324) 83. The crystal structure of bairdite (R1 = 0.072 for 1406 reflections with Fo > 4σF) contains edge-sharing chains of Te6+O6 and Cu2+O6 octahedra parallel to b that are joined by corner-sharing in the a direction, forming thick stair-step-like hexagonal close packed layers parallel to {100}. The polyhedral sheet has similarities to those in the structures of timroseite and paratimroseite. The thick interlayer region contains PbO10 polyhedra and half-occupied SO4 groups. Raman and infrared spectral data are presented [ABSTRACT FROM AUTHOR]

Housleyite, Pb6CuTe4O18(OH)2, is a new tellurate from Otto Mountain near Baker, California, named in honor of Robert M. Housley. The new mineral occurs on fracture surfaces and in small vugs in brecciated quartz veins. Housleyite is directly associated with acanthite, cerussite, gold, iodargyrite, khinite-4O, wulfenite, and three other new tellurates: markcooperite, ottoite, and thorneite. A variety of other secondary minerals occur in the veins, including three other new secondary tellurium minerals, paratimroseite, telluroperite, and timroseite. Housleyite is monoclinic, space group P21/n, a = 7.8552(5), b = 10.4836(7), c = 11.0426(8) Å, β = 95.547(2)°, and Z = 2. Crystals are prismatic to bladed with elongation parallel to b and typically occur in bow tie-like aggregates, drusy balls, and irregular sprays. It is pale to medium greenish blue and transparent, with pale blue streak and adamantine luster. Mohs hardness is estimated at 3. The mineral is brittle, with an irregular fracture. Cleavage was not observed, but is likely on {101̄}. The calculated density is 7.845(1) g/cm³. Housleyite is biaxial (+), with 2V = 50° to 60° and strong inclined dispersion, r > v, but indices of refraction are too high to be measured. The optic orientation is Y = b, Z ˆ c ≈ 40° in obtuse β and pleochroism is Y (medium green-blue) > Z (light green-blue) > X. Energy dispersive spectroscopy provided PbO 62.53, CuO 3.77, TeO3 32.85, H2O 0.84 (structure), total 99.99 wt%.; the empirical formula (based on O = 20) is Pb5.99Cu1.01Te4.00O18(OH)2. The strongest powder X-ray diffraction lines are [dobs in Å (hkl) I]: 3.336 (2̄02, 031, 122) 69, 3.292 (1̄13) 50, 3.195 (130, 103) 100, 3.068 (2̄21, 202) 47, 3.007 (023) 49, 2.942 (032, 212) 80, 2.723 (123, 2̄13, 132) 29, 2.580 (230, 3̄01, 2̄31) 38. The crystal structure (R1 = 0.028) consists of corner-sharing chains of TeO6 octahedra along [101] linked into slabs parallel to {101̄} by sharing edges and corners with strongly Jahn-Teller (4+2) distorted and severely skewed CuO6 octahedra. Lead (Pb) atoms in lopsided nine- and elevenfold coordinations form additional links within and between the octahedral sheets. [ABSTRACT FROM AUTHOR]

The article focuses on the discovery of rare secondary tellurium minerals at the Aga Mine on Otto Mountain by Robert M. Housley which resulted to his exploration along with Richard Thomssen and Joseph Marty. It mentions that the exploration on Otto Mountain which consists of quartz diorite and granitic rocks granodiorite includes the thorneite, markcooperite, and telluroperite. It also presents the primary minerals found on Otto Mountain including Quartz, Calcite, and Tetradynamite.

Timroseite, Pb2Cu52+(Te6+O6) 2(OH)2, and paratimroseite, Pb2Cu42+(Te6+O6)2(H2O)2, are two new tellurates from Otto Mountain near Baker, California. Timroseite is named in honor of Timothy (Tim) P. Rose and paratimroseite is named for its relationship to timroseite. Both new minerals occur on fracture surfaces and in small vugs in brecciated quartz veins. Timroseite is directly associated with acanthite, cerussite, bromine-rich chlorargyrite, chrysocolla, gold, housleyite, iodargyrite, khinite-4O, markcooperite, ottoite, paratimroseite, thorneite, vauquelinite, and wulfenite. Paratimroseite is directly associated with calcite, cerussite, housleyite, khinite-4O, markcooperite, and timroseite. Timroseite is orthorhombic, space group P21nm, a = 5.2000(2), b = 9.6225(4), c = 11.5340(5) Å, V = 577.13(4) ų, and Z = 2. Paratimroseite is orthorhombic, space group P212121, a = 5.1943(4), b = 9.6198(10), c = 11.6746(11) Å, V = 583.35(9) ų, and Z = 2. Timroseite commonly occurs as olive to lime green, irregular, rounded masses and rarely in crystals as dark olive green, equant rhombs, and diamond-shaped plates in subparallel sheaf-like aggregates. It has a very pale yellowish green streak, dull to adamantine luster, a hardness of about 21/2 (Mohs), brittle tenacity, irregular fracture, no cleavage, and a calculated density of 6.981 g/cm³. Paratimroseite occurs as vibrant "neon" green blades typically intergrown in irregular clusters and as lime green botryoids. It has a very pale green streak, dull to adamantine luster, a hardness of about 3 (Mohs), brittle tenacity, irregular fracture, good {001} cleavage, and a calculated density of 6.556 g/cm³. Timroseite is biaxial (+) with a large 2V, indices of refraction > 2, orientation X = b, Y = a, Z = c and pleochroism: X = greenish yellow, Y = yellowish green, Z = dark green (Z > Y > X). Paratimroseite is biaxial (-) with a large 2V, indices of refraction > 2, orientation X = c, Y = b, Z = a and pleochroism: X = light green, Y = green, Z = green (Y = Z >> X). Electron microprobe analysis of timroseite provided PbO 35.85, CuO 29.57, TeO3 27.75, Cl 0.04, H2O 1.38 (structure), O≡Cl -0.01, total 94.58 wt%; the empirical formula (based on O+Cl = 14) is Pb2.07 Cu4.802+Te2.046+O12(OH) 1.98Cl0.02. Electron microprobe analysis of paratimroseite provided PbO 36.11, CuO 26.27, TeO3 29.80, Cl 0.04, H2O 3.01 (structure), O≡Cl -0.01, total 95.22 wt%; the empirical formula (based on O+Cl = 14) is Pb1.94Cu3.962+Te2.036+O 12(H2O)1.99Cl0.01. The strongest powder X-ray diffraction lines for timroseite are [dobs in Å (hkl) I]: 3.693 (022) 43, 3.578 (112) 44, 3.008 (023) 84, 2.950 (113) 88, 2.732 (130) 100, 1.785 (multiple) 33, 1.475 (332) 36; and for paratimroseite 4.771 (101) 76, 4.463 (021) 32, 3.544 (120) 44, 3.029 (023,122) 100, 2.973 (113) 48, 2.665 (131) 41, 2.469 (114) 40, 2.246 (221) 34. The crystal structures of timroseite (R1 = 0.029) and paratimroseite (R1 = 0.039) are very closely related. The structures are based upon edge- and corner-sharing sheets of Te and Cu polyhedra parallel to (001) and the sheets in both structures are identical in topology and virtually identical in geometry. In timroseite, the sheets are joined to one another along c by sharing the apical O atoms of Cu octahedra, as well as by sharing edges and corners with an additional CuO5 square pyramid located between the sheets. The sheets in paratimroseite are joined only via Pb-O and H bonds. [ABSTRACT FROM AUTHOR]

Markcooperite, Pb2(UO2)Te6+O6, is a new tellurate from Otto Mountain near Baker, California, named in honor of Mark A. Cooper of the University of Manitoba for his contributions to mineralogy. The new mineral occurs on fracture surfaces and in small vugs in brecciated quartz veins. Markcooperite is directly associated with bromian chlorargyrite, iodargyrite, khinite-4O, wulfenite, and four other new tellurates: housleyite, thorneite, ottoite, and timroseite. Various other secondary minerals occur in the veins, including two other new secondary tellurium minerals: paratimroseite and telluroperite. Markcooperite is monoclinic, space group P21/c, a = 5.722(2), b = 7.7478(2), c = 7.889(2) Å, β = 90.833(5)°, V = 349.7(2) ų, and Z = 2. It occurs as pseudotetragonal prisms to 0.2 mm with the forms {100} and {011} and as botryoidal intergrowths to 0.3 mm in diameter; no twinning was observed. Markcooperite is orange and transparent, with a light orange streak and adamantine luster, and is non-fluorescent. Mohs hardness is estimated at 3. The mineral is brittle, with an irregular fracture and perfect {100} cleavage. The calculated density is 8.496 g/cm³ based on the empirical formula. Markcooperite is biaxial (+), with indices of refraction α = 2.11, β = 2.12, γ = 2.29 calculated using the Gladstone-Dale relationship, measured α-β birefringence of 0.01 and measured 2V of 30(5)°. The optical orientation is X = c, Y = b, Z = a. The mineral is slightly pleochroic in shades of orange, with absorption: X > Y = Z. No dispersion was observed. Electron microprobe analysis provided PbO 50.07, TeO3 22.64, UO3 25.01, Cl 0.03, O≡Cl -0.01, total 97.74 wt%; the empirical formula (based on O+Cl = 8) is Pb2.05U0.80Te1.186+O7.99 Cl0.01. The strongest powder X-ray diffraction lines are [dobs in Å (hkl) I]: 3.235 (120, 102, 1̄02) 100, 2.873 (200) 40, 2.985 (1̄21, 112, 121) 37, 2.774 (022) 30, 3.501 (021, 012) 29, 2.220 (221, 2̄21, 212) 23, 1.990 (222, 2̄22) 21, and 1.715 (320) 22. The crystal structure (R1 = 0.052) is based on sheets of corner-sharing uranyl square bipyramids and tellurate octahedra, with Pb atoms between the sheets. Markcooperite is the first compound to show Te6+ substitution for U6+ within the same crystallographic site. Markcooperite is structurally related to synthetic Pb(UO2)O2. [ABSTRACT FROM AUTHOR]

Telluroperite, Pb3Te4+O4Cl2, is a new tellurite from Otto Mountain near Baker, California. The new mineral occurs on fracture surfaces and in small vugs in brecciated quartz veins in direct association with acanthite, bromine-rich chlorargyrite, caledonite, cerussite, galena, goethite, and linarite. Various other secondary minerals occur in the veins, including six new tellurates, housleyite, markcooperite, paratimroseite, ottoite, thorneite, and timroseite. Telluroperite is orthorhombic, space group Bmmb, a = 5.5649(6), b = 5.5565(6), c = 12.4750(14) Å, V = 386.37(7) ų, and Z = 2. The new mineral occurs as rounded square tablets and flakes up to 0.25 mm on edge and 0.02 mm thick. The form {001} is prominent and is probably bounded by {100}, {010}, and {110}. It is bluish-green and transparent, with a pale bluish-green streak and adamantine luster. The mineral is non-fluorescent. Mohs hardness is estimated to be between 2 and 3. The mineral is brittle, with a curved fracture and perfect {001} cleavage. The calculated density based on the empirical formula is 7.323 g/cm³. Telluroperite is biaxial (-), with very small 2V (~10°). The average index of refraction is 2.219 calculated by the Gladstone-Dale relationship. The optical orientation is X = c and the mineral exhibits moderate bluish-green pleochrosim; absorption: X < Y = Z. Electron microprobe analysis provided PbO 72.70, TeO2 19.26, Cl 9.44, O≡Cl -2.31, total 99.27 wt%. The empirical formula (based on O+Cl = 6) is Pb2.79Te1.034+O3.72Cl 2.28. The six strongest powder X-ray diffraction lines are [dobs in Å (hkl) I]: 3.750 (111) 58, 2.857 (113) 100, 2.781 (020, 200) 43, 2.075 (024, 204) 31, 1.966 (220) 30, and 1.620 (117, 313, 133) 52. The crystal structure (R1 = 0.056) is based on the Sillén X1 structure-type and consists of a three-dimensional structural topology with lead-oxide halide polyhedra linked to tellurium/lead oxide groups. The mineral is named for the relationship to perite and the dominance of Te (with Pb) in the Bi site of perite. [ABSTRACT FROM AUTHOR]

Ottoite, Pb2TeO5, is a new tellurate from Otto Mountain near Baker, California. Most of the mining on Otto Mountain occurred between 1940 and 1970 and is attributed to Otto Fuetterer, for whom the mountain is now named. The new mineral occurs on fracture surfaces and in small vugs in brecciated quartz veins, which intersect granitic rocks. Ottoite is directly associated with acanthite, bromine-rich chlorargyrite, gold, iodargyrite, khinite, wulfenite, and four other new tellurates: housleyite, mark-cooperite, thorneite, and timroseite. Various other secondary minerals occur in the veins, including two other new secondary tellurium minerals, paratimroseite and telluroperite. Ottoite and most other secondary minerals of the quartz veins are interpreted as having formed from the partial oxidation of primary sulfides and tellurides during or following brecciation of the veins. A later generation of quartz mineralization then recemented the breccias, effectively isolating and protecting the secondary mineralization from further alteration. Ottoite is monoclinic, space group I2/a, with the unit cell: a = 7.5353(6), b = 5.7142(5), c = 10.8981(12) Å, β = 91.330(6)°, V = 469.13(8) ų, and Z = 4. The mineral occurs as complex spear-shaped crystals in subparallel to divergent intergrowths. It is yellow and transparent to translucent, with a pale yellow streak and adamantine luster. Mohs hardness is estimated at 3. The mineral is brittle, with an irregular fracture and two cleavages in the [100] zone at ~90°--possibly on {010} and {001}. The calculated density is 8.721 g/cm³. Ottoite is biaxial (-), with a large 2V, but indices of refraction are too high to be measured. The optic orientation could only partially be determined: Y≈a. No pleochroism was observed. Electron microprobe analyses provided the following averages: PbO 68.88 and TeO3 28.03, total 96.95 wt%; the empirical formula (based on O = 5) is Pb1.96Te1.016+O5. The strongest powder X-ray diffraction lines are [dobs in Å (hkl) I]: 3.131 (2̄02) 64, 3.055 (013) 90, 3.015 (211) 100, 2.112 (2̄22) 29, 1.810 (006, 2̄15) 21, 1.773 (4̄11, 402) 43, 1.686 (033, 231) 20. The crystal structure (R1 = 0.020) consists of straight chains of trans-corner-sharing Te6+O6 octahedra parallel to a, which are joined by bonds to Pb atoms. The Pb atom exhibit markedly lopsided 11-coordination, typical of Pb2+ with stereoactive 6s² lone-pair electrons. The powder X-ray diffraction pattern of ottoite is very similar to that reported for girdite. Examination of girdite type material suggests that its description was based upon data obtained from at least two and possibly three different phases, one of which may correspond to ottoite. [ABSTRACT FROM AUTHOR]