CLARINGBULLITE: A Cu2+ OXYSALT WITH Cu2+ IN TRIGONAL-PRISMATIC COORDINATION
PETER C. BURNS*, MARK A. COOPER & FRANK C. HAWTHORNE
Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2
*Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, U.K.
Abstract
The crystal structure of claringbullite, Cu4Cl[Cl0.29(OH)0.71](OH)6, hexagonal,
a 6.6733(5), c 9.185(1) Å, V 354.22(6) Å3, Z = 2, space group P63/mmc, has been solved by trial-and-error methods
and refined by least- squares methods to an R index of 3.4%, a wR index of 3.2%, and an S factor of
1.35 using 227 unique observed [I 2.5 (I)] reflections. The chemical formula of claringbullite has been revised as
a result of this determination of the crystal structure. Claringbullite contains two Cu positions. The Cu(1)
position is octahedrally coordinated by four (OH) groups and two Cl atoms. The Cl(1) atoms are located
in the apical positions of a (4 + 2)-distorted octahedron, the distortion of which is attributed to the
Jahn-Teller effect. The Cu(2) position is coordinated by six (OH) groups in a distorted trigonal prismatic arrangement. The
Cu(1) 6 octahedra share edges to form sheets of octahedra parallel to (001), with every fourth
octahedral site vacant. These sheets of octahedra share Cl atoms along [001], and thus claringbullite
has a framework structure. The stacking of sheets of octahedra is such that the holes in the sheets are
collinear, forming channels through the structure parallel to [001]. The Cl(2) position, which is partially occupied
by (OH), is located in these channels, at a point midway between the sheets of octahedra. The Cu(2) position
is located between the sheets, further linking the [Cu(1)3 ] 8 sheets of octahedra into a framework.
Keywords: claringbullite, copper oxysalt, crystal structure, Bisbee, Arizona.