The informal discreditation of “doranite” as the magnesium analog of analcime

Abstract

Zeolites that fill vugs in basalt from the type locality of “doranite” near Carrickfergus, UK, were reexamined with the hope of establishing the magnesium analog of analcime as a valid species. However, contents of Mg in the zeolites as measured by electron microprobe analysis were not above the limits of detection (0.01 wt% MgO). X-ray powder diffraction and optical microscopy show a vug assemblage of thomsonite + natrolite + analcime + Mg-rich clay minerals.