Sapphirine Structure

Steven Dutch, Natural and Applied Sciences, University of Wisconsin - Green Bay
First-time Visitors: Please visit Site Map and Disclaimer. Use "Back" to return here.


Sapphirine (Mg,Al)8(Al,Si)6O20 is a metamorphic mineral. It consists of branched single chains of silica tetrahedra (purple) and aluminum tetrahedra (blue). Aluminum octahedra (yellow) link the chains.

Below: The silica chain layers alternate with layers of aluminum (yellow) and magnesium (green) octahedra.

The sapphirine structure is approximately close-packed. Above is a silica-aluminum layer with one plane of oxygen atoms indicated in blue. Below is a magnesium-aluminum octahedra layer with two planes of oxygen atoms. Atoms further from the plane of view are lighter. In both views the polyhedra are shown in light colors.

Below: Diagram showing how the silica and octahedral layers connect.

 

Below: view down the [102] zone, showing the pseudo-rhombic structure. Background polyhedra are lighter.

Below: view down the c-axis, showing alternation of the octahedral and tetrahedral layers.

Below: view down the a-axis, showing the approximate close-packed structure. Octahedra are yellow and gree, tetrahedra are purple and blue.


Return to Thin-Section Index
Return to Crystal Structures Index
Return to Mineral Identification Tables
Return to Professor Dutch's Home Page

Created 22 April 2013, Last Update 10 Jul 2013

Not an official UW Green Bay site