Abstract

Single crystal X-ray photographs of purple kämmererite from the Day Book Body, Yancey County, North Carolina exhibit cell dimensions of a0 = 5.24 ± 0.01 Å, b0 = 9.17 ± 0.01 Å, c0 = 14.39 ± 0.1 Å, β = 97°5′. A chemical analysis yields a structural formula of [Al1.7Cr0.4Mg9.5Fe0.2Ni0.7]VIII12.5 [Si6.5Cr0.5Al1.0]IV8O20.8(OH)15.7. Since the Cr was neither predominantly tetrahedral nor predominantly octahedral it could not be classified by Lapham's classification. The author proposes that traditional meanings of kämmererite and kotschubeite be preserved and extendedso that kämmererite contains CrVI ≥ CrIV (in number of atoms)a nd kotschubeite contains CrVI < CrIV (in number of atoms).

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