Agardite-(Y), Cu(2+) 6Y(AsO4)3(OH)6·3H2O

Area of Science:

• Mineralogy
• Crystallography
• Geochemistry

Background:

• Agardite-(Y) is a mineral belonging to the mixite group, with the general formula Cu(2+) 6 A(TO4)3(OH)6·3H2O.
• The A-site typically contains rare earth elements, Al, Ca, Pb, or Bi, while the T-site contains P or As.

Purpose of the Study:

• To present the first structure determination of agardite-(Y).
• To analyze the structural characteristics of agardite-(Y) using single-crystal X-ray diffraction.

Main Methods:

• Single-crystal X-ray diffraction was performed on a natural sample of agardite-(Y).
• The sample was sourced from the Jote West mine, Pampa Larga Mining District, Copiapo, Chile.

Main Results:

• The refined formula for agardite-(Y) is Cu(2+) 5.70(Y0.69Ca0.31)[(As0.83P0.17)O4]3(OH)6·3H2O.
• The structure features infinite chains of edge-sharing CuO5 square pyramids along the c axis.
• These chains are linked by edge-sharing YO9 polyhedra and corner-sharing AsO4 tetrahedra in the ab plane.
• Tubular channels containing lattice water molecules are present, with walls formed by CuO5 and AsO4 polyhedra.

Conclusions:

• This study provides the first detailed structural analysis of agardite-(Y).
• The findings elucidate the complex arrangement of polyhedra and channels within the agardite-(Y) structure.
• The research contributes to the understanding of the mixite mineral group's crystallography.