Pectolite Structure

Steven Dutch, Natural and Applied Sciences, University of Wisconsin - Green Bay
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In terms of its chemisty and associations, pectolite seems akin to the zeolites, but it is actually a pyroxenoid. It's a silicate of calcium and sodium, both large cations, and therefore has to deal with the size issue much the same way that wollasonite does, by canting the tetrahedra until they link up. But unlike wollastonite, pectolite includes sodium.

The sodium atoms separate strips of Ca-O octahedra. In the diagram below, yellow polhedra are filled with calcium, organge with sodium. Blue spheres are hydrogen atoms because some oxygen locations are occupied by hydroxyl.

The figure below shows how the silica chains (pink) are kinked to accomodate the large cation polyhedra.

Below, the silica chains are shown in isolation.

Below, an end-on view of the structure.

Below, longitudinal view of the structure, showing the canting of the tetrahedra.


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Created 10 Oct 1997, Last Update 16 December 1999

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