The crystal structure of tedhadleyite, Hg²⁺Hg¹⁺₁₀O₄I₂(Cl,Br)₂, from the Clear Creek Claim, San Benito County, California

Authors: Cooper, M.A.; Hawthorne, F.C.

Source: Mineralogical Magazine, Volume 73, Number 2, April 2009 , pp. 227-234(8)

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Abstract:

The crystal structure of tedhadleyite, ideally Hg²⁺Hg⁺₁₀O₄I₂(Cl,Br)₂, triclinic, A1, a 7.0147(5), b 11.8508(7), c 12.5985(8) Å, α 115.583(5), β 82.575(2), γ 100.619(2)°, V 927.0(2) Å³, Z = 2, was solved by direct methods and refined to an R₁ index of 4.5% for 2677 unique reflections. There are six symmetrically distinct Hg sites in tedhadleyite: Hg(1) is occupied by Hg²⁺ and Hg(2-6) are occupied by Hg⁺ that forms three [Hg-Hg]²⁺ dimers with Hg-Hg separations between 2.527 and 2.556 Å. These [Hg-Hg]²⁺ dimers have strong covalent bonds to O atoms, forming pseudo-linear O-Hg-Hg-O arrangements, and weak bonds to halogen and O atoms at high angles to the dimer axis. The [O-Hg-Hg-O] groups share anions to form four-membered square rings of composition [Hg₈O₄] that link along [100] via [O-Hg-Hg-O] groups and along [001] via [O-Hg-O] groups, forming rectangular rings of composition [Hg₁₄O₈]. The rings form a corrugated layer that interweaves with a symmetrically related layer whereby the [O-Hg(6)-Hg(6)-O] linking groups of one layer pass through the centres of the square [Hg₈O₄] rings of the other layer to form [Hg₁₁O₄] complex slabs parallel to (010) that link through Hg-I and Hg-Br, Cl bonds.

Keywords: TEDHADLEYITE; CRYSTAL STRUCTURE; MERCURY MINERAL; SAN BENITO COUNTY; CALIFORNIA

Document Type: Research article

DOI: http://dx.doi.org/10.1180/minmag.2009.073.2.227

Publication date: 2009-04-01

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