Steven Dutch, Professor Emeritus, Natural and Applied Sciences, University of Wisconsin - Green Bay
Turquoise, that perennial staple of Southwestern jewelry, is a hydrous copper-aluminum phosphate with formula CuAl6(PO4)4(OH)8*4H2O
The structure is based on zigzag chains of aluminum octahedra (yellow). The chains consist of pairs of octahedra joined edge to edge, and connected by single octahedra sharing a vertex at each end.
The aluminum chains are paired, joined by copper octahedra (green) atop each pair of edge-joined aluminum octahedra.
Viewed from the ends, the aluminum-copper chains look like I-beams. Three different ways of showing the raltionship between the copper atoms and the aluminum chains are shown.
Viewed from the sides, the aluminum-copper chains have a ladder structure.
In the three views above, the aluminum-copper chains are linked by PO4 tetrahedra (brown). Hydrogen atoms are red.
In the three views above, hydrogen atoms are red.
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Created 06 March 2016, Last Update
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