Undefined pseudomorph after sodalite

Occurs as white or milky cloudy, isometric crystal formations. Often colorless, water-clear, isometric, analyzed sodalite crystals occur in direct paragenesis. For this reason, and because of their crystal morphology, it is assumed that the white crystal formations are former sodalite crystals.

Despite the often well-formed faces, these crystal formations are X-ray amorphous in the cases examined by us (23 PXRD analyses on "crystals" from different localities). Their chemical composition no longer corresponds to that of sodalite (different compositions, no Cl and S, but often high Al and Si contents).

This mixture are only found in former clay rock inclusions (recognizable e.g. by occurrences of topaz/mullite in the paragenesis) of the volcanic Eifel, Germany, are almost always wrongly called sodalite.

White or milky cloudy crystals that occur in pores or the matrix of slags, welding slags or in other silicate or calcium-rich inclusions are different from this phase.