THE INFORMAL DISCREDITATION OF DORANITE AS THE MAGNESIUM ANALOG OF ANALCIME

Zeolites that fill vugs in basalt from the type locality of ''doranite '' near Carrickfergus, UK, were reexamined with the hope of establishi ng the magnesium analog of analcime as a valid species. However, conte nts 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 di ffraction and optical microscopy show a vug assemblage of thomsonite natrolite + analcime + Mg-rich clay minerals.