Copper(I) Sulfide - Structure

Structure

There are two forms of Cu2S a low temperature monoclinic form ("low-chalcocite") which has a complex structure with 96 copper atoms in the unit cell and a hexagonal form stable above 104°C. In this structure there are 24 crystallographically distinct Cu atoms and the structure has been described as approximating to a hexagonal close packed array of sulfur atoms with Cu atoms in planar 3 coordination. This structure was initially assigned an orthorhombic cell due to the twinning of the sample crystal.

There is also a crystallographically-distinct phase (the mineral djurleite) with stoichiometry Cu1.96S which is non-stoichiometric (range Cu1.934S-Cu1.965S) and has a monoclinic structure with 248 copper and 128 sulfur atoms in the unit cell. Cu2S and Cu1.96S are similar in appearance and hard to distinguish one from another.

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