Zinc and iron end-member staurolites, as well as three Fe/Zn staurolites with intermediate compositions, have been synthesized in a tetrahedral press at approximately 30 kbar and 750°C. All are dimensionally orthorhombic, but are assumed to be monoclinic by analogy with natural staurolites. Indices of refraction of zinc staurolite are α = 1.683, β = 1.694, γ = 1.700. Lattice parameters for the Fe/Zn series vary linearly with composition, in general consonance with previous models of staurolite crystal chemistry. Disorder of Zn and Fe2+ is tentatively suggested by molar volume data. The effective ionic radius of tetrahedrally-coordinated Zn2+ is 0.57Å (±0.01Å) based on unit cell volumes of synthetic staurolites and on previously published data for Zn2+ tetrahedral oxyanions.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not have access to this content, please speak to your institutional administrator if you feel you should have access.