Freudenbergite

Freudenbergite is a mineral that is named in honor of Wilhelm Freudenberg, palaeontologist at the University of Tübingen and the University of Göttingen, and curator for mineralogy and geology at the National Collections of Natural History in Karlsruhe. He studied Katzenbuckel rocks.

Naturally occurring freudenbergite is a solid solution of two end members Na2Fe +32Ti6O16 and Na2Fe +2Ti7O16, which were referred to as low-Ti and high-Ti freudenbergite, respectively Both varieties were found in the course of close examination of samples from the Katzenbuckel Complex, Germany, in which this mineral was documented for the first time As a possible mineral Fe2+ analog was named UM1983-07-O:FeNaTi

Monoclinic with straight extinction and high birefringence. Brown.

Synthetic freudenbergite was crystallized during the lamprophyllite incongruity melting.