The crystal structure of comancheite, Hg2+55N3–24(OH, NH2)4(Cl,Br)34, orthorhombic, space group Pnnm, a = 18.414(5), b = 21.328(6), c = 6.6976(19) Å, V = 2630(2) Å3, Z = 1, was solved by direct methods and refined to an R1 index of 4.3% based on 4160 unique observed reflections. In the structure of comancheite, there are nine crystallographically distinct Hg2+ cations, each of which is coordinated by two N3– anions to form near-linear N3––Hg2+–N3– groups. Four other crystallographically distinct Hg2+ cations are coordinated by a mixture of N3–, O2–, (OH)– and (NH2)– anions, and there is a small amount of [Hg–Hg]2+ dimer. In addition, there are eight crystallographically distinct halogen sites, three of which are completely occupied by Cl–, and five of which are occupied by both Cl– and Br–. The principal anion, N3–, shows a strong preference for tetrahedral coordination by Hg2+, which results in a strongly bonded three-dimensional {–Hg2+–N3––} framework. This framework is both interrupted and contains large interstices that incorporate additional Hg2+ cations, a very small amount of [Hg+–Hg+]2+ dimer and additional anion species, O2–, (OH)– and (NH2)–, that coordinate Hg2+.

Comancheite was described originally as an Hg-oxide mineral. The major change in chemical composition indicated by the present work was approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (Voting Proposal 13-B). The presence of N provides some analytical challenges, particularly in the presence of Hg. New bond-valence parameters were derived for Hg2+–N3– bonds [Ro(N3–) = 1.95] using well refined Hg2+ structures, and this allows discrimination between Hg2+–O2– and Hg2+–N3– bonds based on the valence-sum rule. Comparison of the Raman spectra of several Hg-bearing minerals shows that peaks in the range 500–700 cm–1 are characteristic of Hg2+–N3– stretching vibrations whereas peaks in the range 350–500 cm–1 are characteristic of Hg2+–O2– stretching vibrations; Hg2+–O2– and Hg2+ – N3– bonds may be discriminated on this basis.

The new mineral leverettite (IMA 2013-011), ideally Cu3CoCl2(OH)6, was found at the Torrecillas mine, Salar Grande, Iquique Province, Chile, where it occurs as a supergene alteration phase in association with akaganéite, anhydrite, chalcophanite, goethite, halite, manganite, pyrite, quartz and todorokite. Crystals of leverettite are steep rhombohedra to 1 mm with {101} prominent and modified by {001}, sometimes forming V-shaped twins by reflection on {10}. The crystals can also form finger-like, parallel stacked growths along the c axis. The new mineral is medium to deep green in colour and has a light green streak. Crystals are transparent with a vitreous lustre. Mohs hardness is ∼3 and the crystals have a brittle tenacity, a perfect cleavage on {101} and a conchoidal fracture. The measured density is 3.64(2) g cm–3 and calculated density based on the empirical formula is 3.709 g cm–3. Optically, leverettite is uniaxial (–) with ω and ε > 1.8 and exhibits pleochroism with O (bluish green) > E (slightly yellowish green). The empirical formula, determined from electron-microprobe analyses is Cu3(Co0.43Cu0.40Mn0.17Ni0.07Mg0.01)Σ1.08Cl1.87O6.13H6. Leverettite is trigonal (hexagonal), space group Rm, unit-cell parameters a = 6.8436(6) and c = 14.064(1) Å, V = 570.42(8) Å3, Z = 3. The eight strongest X-ray powder diffraction lines are [dobs Å (I)(hkl)]: 5.469(90)(101), 4.701(18)(003), 2.905(22)(021), 2.766(100)(113), 2.269(66)(024), 1.822(26)(033), 1.711(33)(220), 1.383(23)(128). The structure, refined to R1 = 0.023 for 183 Fo > 4σF reflections, shows leverettite to be isostructural with herbertsmithite and gillardite.

Yellow needles of 'iodolaurionite', Pb(OH)I, and a novel compound Pb2O(OH)I, have been prepared by hydrothermal reactions of PbO and PbI2 at 170°C. The crystal structure of 'iodolaurionite', Pb(OH)I (orthorhombic, Pnma, a = 7.8244(8), b = 4.2107(4), c = 10.4724(10) Å, V = 345.03(6) Å3, Z = 4) has been refined to R1 = 0.041 for 129 independent observed reflections. The structure is based on the OHPb3 triangles sharing common edges to produce single [OHPb]+ chains extending along the b axis and parallel to the ab plane. The three-dimensional integrity of the structure is provided by the Pb–I bonds and the O–H···I hydrogen bonding. The structure is isotypic with that of laurionite, Pb(OH)Cl. The crystal structure of Pb2O(OH)I (monoclinic, C2/m, a = 13.711(3), b = 4.0975(10), c = 9.584(2) Å, β = 110.64(1)°, V = 503.9(2) Å3, Z = 4), has been solved by direct methods and refined to R1 = 0.053 for 586 independent observed reflections. In the structure of Pb2O(OH)I, O(1)Pb4 tetrahedra link together by sharing edges and corners to form [OPb2]2+ chains similar to those observed in sidpietersite. The O(2) atoms belong to hydroxyl groups attached to both sides of the chains to produce novel [O(OH)Pb2]+ 1D units. The [O(OH)Pb2]+ units are extended parallel to the b axis and lie within the bc plane. The [O(OH)Pb2]+ units are linked together via hydrogen bonding in the (100) plane and by weak Pb–I bonds in the [100] direction. The [O(OH)Pb2]+ bands can be obtained from the [OPb] layer of OPb4 tetrahedra present in the structure of tetragonal PbO (litharge). The continuous [OPb] layer has to be broken into [O2Pb2] bands containing 3- and 4-coordinated O atoms in the 1:1 ratio with subsequent protonation of the 3-coordinated O sites. Relations of Pb(OH)I and Pb2O(OH)I to known Pb hydroxy- and oxyhalides are described briefly.