Structure and twinning in spencerite

• Main Authors: L. Fanfani, A. Nunzi, P F. Zanazzi, Was Performed
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Hudson; Hudson Bay
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.614.3004; http://www.minersoc.org/pages/Archive-MM/Volume_38/38-298-687.pdf

on a twin crystal from Salmo, British Columbia. Three-dimensional intensity data were collected by a Weissenberg apparatus. The R index was o'098 for 335 independent observed reflections. The crystal structure previously determined is essentially confirmed. Co-ordination around Zn is both octahedral and tetrahedral. The atomic arrangement consists of complex sheets of co-ordination octahedra and tetrahedra around Zn and P atoms connected by layers of water molecules. The frequent occurrence of twinning in spencerite is explained from structural considerations. SVENCE~ITE, a natural hydrated basic zinc phosphate with chemical formula Zn4(PO~)2(OH)~-3H20, was first found by Walker 0916) at the Hudson Bay mine, Salmo, British Columbia, where it occurs as polysynthetic aggregates with twin plane and composition surface {IOO}. The morphology suggests a monoclinic symmetry. In a recent investigation Niebsch (I966) determined the lattice parameters and the space group of the mineral (P2/c), and proposed an approximate structural model based on limited data. The purpose of our work is to refine the structure of spencerite using more data and to relate the structure and twinning in the mineral.