Abstract

Members of the crandallite group of aluminous hydroxy phosphates are present in trace amounts in every formation of the Athabasca Group in Alberta. The minerals of the group present in Alberta form a solid-solution series with end members goyazite (SrAl3(PO4)OH5), crandallite (CaAl3(PO4)OH5), and gorceixite (BaAl3(PO4)OH5). These minerals are present as cubes and subhedral grains, 2–20 μm across, in isolation or in clusters interstitially in the Athabasca Group sandstones, siltstones, and tuffs. Petrographic study indicates an authigenic origin for the crandallite-group minerals in the Athabasca Group. Their presence, locally, beneath quartz overgrowths and early diagenetic fluorapatite suggests formation very early in the post-depositional history of the rock. The presence of the crandallites within the regolith beneath the Athabasca Group and within a metamorphic rock fragment incorporated into the sandstone suggests more than one origin for the minerals and possibly a detrital component.

You do not currently have access to this article.