Posted on February 28, 2017 by John J. Bradshaw, GG (GIA)

Introduction Hackmanite, Na8Al6Si6O24(Cl2,S), is the rare variety of the mineral species sodalite. Sodalite is a translucent to opaque, dark blue to violet-blue material that is used for jewelry purposes, typically fashioned as cabochons or beads, while…

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