Plumbophyllite, a new species from the Blue Bell claims near Baker, San Bernardino County, California

The new mineral plumbophyllite, Pb2Si4O10·H2O, orthorhombic with space group Pbcn and cell parameters a = 13.2083(4), b = 9.7832(3), c = 8.6545(2) Å, V = 1118.33(5) Å^3, and Z = 4. It occurs as colorless to pale blue prismatic crystals to 3 mm, with wedge-shaped terminations at the Blue Bell claims, about 11 km west of Baker, San Bernardino County, California. It is found in narrow veins in a highly siliceous hornfels in association with cerussite, chrysocolla, fluorite, goethite, gypsum, mimetite, opal, plumbotsumite, quartz, sepiolite, and wulfenite. The streak is white, the luster is vitreous, the Mohs hardness is about 5, and there is one perfect cleavage, {100}. The measured density is 3.96(5) g/cm^3 and the calculated density is 3.940 g/cm^3. Optical properties (589 nm): biaxial (+), {alpha} = 1.674(2), β = 1.684(2), {gamma} = 1.708(2), 2V = 66(2)°, dispersion r > v (strong); X = b, Y = c, Z = a. Electron microprobe analysis provided PbO 60.25, CuO 0.23, SiO_2 36.22 wt%, and CHN analysis provided H_2O 3.29 wt% for a total of 99.99 wt%. Powder IR spectroscopy confirmed the presence of H_2O and single-crystal IR spectroscopy indicated the H_2O to be oriented perpendicular to the b axis. Raman spectra were also obtained. The strongest powder X-ray diffraction lines are [d (hkl) I]: 7.88(110)97, 6.63(200)35, 4.90(020)38, 3.623(202)100, 3.166(130)45, 2.938(312/411/222)57, 2.555(132/213)51, and 2.243(521/332)50. The atomic structure (R1 = 2.04%) consists of undulating sheets of silicate tetrahedra between which are located Pb atoms and channels containing H_2O (and Pb^(2+) lone-pair electrons). The silicate sheets can be described as consisting of zigzag pyroxene-like (SiO_3)_n chains joined laterally into sheets with the unshared tetrahedral apices in successive chains pointed alternately up and down, a configuration also found in pentagonite

Lead-tellurium oxysalts from Otto Mountain near Baker, California: IV. Markcooperite, Pb(UO_2)Te^(6+)O_6, the first natural uranyl tellurate

Markcooperite, Pb_2(UO_2)Te^(6+)O_6, 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 P2_1/c, a = 5.722(2), b = 7.7478(2), c = 7.889(2) Å, β = 90.833(5)°, V = 349.7(2) Å^3, 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, TeO_3 22.64, UO_3 25.01, Cl 0.03, O≡Cl –0.01, total 97.74 wt%; the empirical formula (based on O+Cl = 8) is Pb_(2.05)U_(0.80)Te^(6+)_(1.18)O_(7.99)Cl_(0.01). The strongest powder X-ray diffraction lines are [d_(obs) in Å (hkl) I]: 3.235 (120, 102, 1[overbar]02) 100, 2.873 (200) 40, 2.985 (1[overbar]21, 112, 121) 37, 2.774 (022) 30, 3.501 (021, 012) 29, 2.220 (221, 2[overbar]21, 212) 23, 1.990 (222, 2[overbar]22) 21, and 1.715 (320) 22. The crystal structure (R_1 = 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 Te^(6+) substitution for U^(6+) within the same crystallographic site. Markcooperite is structurally related to synthetic Pb(UO_2)O_2

Lead-tellurium oxysalts from Otto Mountain near Baker, California: V. Timroseite, Pb_2Cu_5^(2+)(Te^(6+)O_6)_2(OH)_2, and paratimroseite, Pb_2Cu_4^(2+)(Te^(6+)O_6)_2(H_2O)_2, two new tellurates with Te-Cu polyhedral sheets

Timroseite, Pb_2Cu_5^(2+)(Te^(6+)O_6)_2(OH)_2, and paratimroseite, Pb_2Cu_4^(2+)(Te^(6+)O_6)_2(H_2O)_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 P2_1nm, a = 5.2000(2), b = 9.6225(4), c = 11.5340(5) Å, V = 577.13(4) Å^3, and Z = 2. Paratimroseite is orthorhombic, space group P2_12_12_1, a = 5.1943(4), b = 9.6198(10), c = 11.6746(11) Å, V = 583.35(9) Å^3, 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 2 1/2 (Mohs), brittle tenacity, irregular fracture, no cleavage, and a calculated density of 6.981 g/cm^3. 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/cm^3. 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, TeO_3 27.75, Cl 0.04, H_2O 1.38 (structure), O≡Cl –0.01, total 94.58 wt%; the empirical formula (based on O+Cl = 14) is Pb_(2.07) Cu^(2+)_(4.80)Te^(6+)_(2.04)O_(12)(OH)_(1.98)Cl_(0.02). Electron microprobe analysis of paratimroseite provided PbO 36.11, CuO 26.27, TeO_3 29.80, Cl 0.04, H_2O 3.01 (structure), O≡Cl –0.01, total 95.22 wt%; the empirical formula (based on O+Cl = 14) is Pb_(1.94)Cu^(2+)_(3.96)Te^(6+)_(2.03)O_(12)(H_2O)_(1.99)Cl_(0.01). The strongest powder X-ray diffraction lines for timroseite are [d_(obs) 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 (R_1 = 0.029) and paratimroseite (R_1 = 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 CuO_5 square pyramid located between the sheets. The sheets in paratimroseite are joined only via Pb-O and H bonds

Lead-tellurium oxysalts from Otto Mountain near Baker, California: VI. Telluroperite, Pb_3Te^(4+)O_4Cl_2, the Te analog of perite and nadorite

Telluroperite, Pb_3Te^(4+)O_4Cl_2, 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) Å^3, 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/cm^3. 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, TeO_2 19.26, Cl 9.44, O≡Cl –2.31, total 99.27 wt%. The empirical formula (based on O+Cl = 6) is Pb_(2.79)Te_(1.03)^(4+)O_(3.72)Cl_(2.28). The six strongest powder X-ray diffraction lines are [d_(obs) 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 (R_1 = 0.056) is based on the Sillén X_1 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

Crystal structure and revised chemical formula for burckhardtite, Pb_2(Fe^(3+)Te^(6+))[AlSi_3O_8]O_6: a double-sheet silicate with intercalated phyllotellurate layers

The crystal structure of burckhardite from the type locality, Moctezuma, Sonora, Mexico, has been refined to R_1 = 0.0362 and wR_2 = 0.0370 for 215 reflections with I > 2σ(I). Burckhardtite is trigonal, space group P3lm, with the unit-cell parameters ɑ = 5.2566(5) Å, c = 13.0221(10) Å, V = 311.62(5) Å3 and Z = 1 for the ideal formula unit Pb_2(Fe^(3+)Te^(6+))[AlSi_3O_8]O_6. There is no long-range order of (Fe^(3+), Te^(6+)) or (Al^(3+), Si^(4+)). 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 [(Fe^(3+)Te^(6+))O_6]^(3−) part of the structure is not bonded directly to the aluminosilicate layer, but forms a discrete anionic phyllotellurate layer that alternates with the [AlSi_3O_8]^− double sheets. Similar phyllotellurate layers are known from several synthetic phases. In burckhardtite, Pb^(2+) cations intercalate between phyllosilicate and phyllotellurate layers, forming a Pb_2[FeTeO_6] module that is topologically similar to a slab of the structure of rosiaite, Pb[Sb_2O_6]. 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 H_2O, are all new findings for the mineral

Lead-tellurium oxysalts from Otto Mountain near Baker, California, USA: XII. Andychristyite, PbCu^(2+)Te^(6+)O_5(H_2O), a new mineral with hcp stair-step layers

Andychristyite, PbCu^(2+)Te^(6+)O_5(H_2O), is a new tellurate mineral from Otto Mountain near Baker, California, USA. It occurs in vugs in quartz in association with timroseite. It is interpreted as having formed from the partial oxidation of primary sulfides and tellurides during or following brecciation of quartz veins. Andychristyite is triclinic, space group P1, with unit-cell dimensions a = 5.322(3), b = 7.098(4), c = 7.511(4) Å, α = 83.486(7), β = 76.279(5), γ = 70.742(5)°, V = 260.0(2) Å^3 and Z = 2. It forms as small tabular crystals up to ∼50 µm across, in sub-parallel aggregates. The colour is bluish green and the streak is very pale bluish green. Crystals are transparent with adamantine lustre. The Mohs hardness is estimated at between 2 and 3. Andychristyite is brittle with an irregular fracture and one perfect cleavage on {001}. The calculated density based on the empirical formula is 6.304 g/cm^3. The mineral is optically biaxial, with large 2V, strong dispersion, and moderate very pale blue-green to medium blue-green pleochroism. The electron microprobe analyses (average of five) provided: PbO 43.21, CuO 15.38, TeO_3 35.29, H_2O 3.49 (structure), total 97.37 wt.%. The empirical formula (based on 6 O apfu) is: Pb_(0.98)C u^(2+)_(0.98)Te^(6+)_(1.02)O_6H_(1.96). The Raman spectrum exhibits prominent features consistent with the mineral being a tellurate, as well as an OH stretching feature confirming a hydrous component. The eight strongest powder X-ray diffraction lines are [d_(obs) in Å(I)(hkl)]: 6.71(16)(010), 4.76(17)(110), 3.274(100)(120,102,012), 2.641(27)(102, 211, 112), 2.434(23)(multiple), 1.6736(17)(multiple), 1.5882(21)(multiple) and 1.5133(15)(multiple). The crystal structure of andychristyite (R_1 = 0.0165 for 1511 reflections with Fo > 4σF) consists of stair-step-like hcp polyhedral layers of Te^(6+)O_6 and Cu^(2+)O_6 octahedra parallel to {001}, which are linked in the [001] direction by bonds to interlayer Pb atoms. The structures of eckhardite, bairdite, timroseite and paratimroseite also contain stair-step-like hcp polyhedral layers

Lead-tellurium oxysalts from Otto Mountain near Baker, California: III. Thorneite, Pb_6(Te_2^(6+)O_(10))(CO_3)Cl_2(H_2O), the first mineral with edge-sharing octahedral tellurate dimers

Thorneite, Pb_6(Te_2^(6+)O_(10))(CO_3)Cl_2(H_2O), is a new tellurate from Otto Mountain near Baker, California, named in honor of Brent Thorne. The new mineral occurs on fracture surfaces and in small vugs in brecciated quartz veins. Thorneite is directly associated with acanthite, cerussite, gold, hessite, iodargyrite, khinite, wulfenite, and three other new tellurates: housleyite, markcooperite, and ottoite. Various other secondary minerals occur in the veins, including three other new secondary tellurium minerals: paratimroseite, telluroperite, and timroseite. Thorneite is monoclinic, space group C2/c, a = 21.305(1), b = 11.059(1), c = 7.564(1) Å, β = 101.112(4)°, V = 1748.8(4) Å^3, and Z = 4. Crystals are prismatic to bladed with elongation and striations parallel to c and typically occur in parallel and random aggregates. It is yellow and transparent, with pale yellow streak and adamantine luster. Mohs hardness is estimated at 2. The mineral is brittle, with an irregular to splintery fracture and good {100} cleavage. The calculated density is 6.828 g/cm^3. Thorneite is biaxial (+), with large 2V, but indices of refraction are too high to be measured. The optic orientation is Y = b, Z ^ a = 29° in obtuse β. No pleochroism was observed. Electron microprobe analysis provided PbO 73.90, ZnO 0.03, TeO_3 20.35, Cl 2.29, H_2O 1.28 (structure), CO_2 2.29 (structure), O≡Cl –0.52, total 99.62 wt%; the empirical formula (based on O+Cl = 16) is (Pb_(5.94)Zn_(0.01))(Te_(2.08)^(6+)O_(10))(C_(1.00)O_3)[Cl_(1.16)O_(0.34)(OH)_(0.50)](H_2O). The strongest powder X-ray diffraction lines are [d_(obs) in Å (hkl) I]: 10.43 (200) 35, 3.733 (5[overbar]11, 2[overbar]02, 002) 27, 3.595 (4[overbar]21) 33, 3.351 (112) 66, 3.224 (511, 131) 100, 3.093 (2[overbar]22, 3[overbar]31) 30, 2.900 (6[overbar]21) 44, 2.133 (821, 622, 223, 731, 242) 38. The crystal structure (R_1 = 0.028) contains edge-sharing octahedral tellurate dimers, [Te_2^(6+)O_(10)]^(8–) that bond to Pb atoms, which in turn are linked via bonds to Cl atoms, CO_3 triangles, and H_2O molecules

The relationship between mineral composition, crystal structure and paragenetic sequence: the case of secondary Te mineralization at the Bird Nest drift, Otto Mountain, California, USA

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^–, CO_3^(2–), SO_4^(2–) and Fe^(3+) 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 Te^(4+) or Te^(6+) oxyanion, while the other also included small, strongly-bound cations such as Cu^(2+). 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' Cu^(2+) 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

The relationship between mineral composition, crystal structure and paragenetic sequence: the case of secondary Te mineralization at the Bird Nest drift, Otto Mountain, California, USA

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^–, CO_3^(2–), SO_4^(2–) and Fe^(3+) 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 Te^(4+) or Te^(6+) oxyanion, while the other also included small, strongly-bound cations such as Cu^(2+). 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' Cu^(2+) 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