Xenotime from Morrua, Mozambique

Abstract

Xenotime, found as well formed crystals in a heavy mineral concentrate from the Morrua pegmatite mine in Mozambique, was studied. The mineral occurs in the sample in two generations, clearly distinguishable from each other. The first generation crystals are turbid with varying color and are dominated by the faces (110) and (001). The second generation crystals are yellow, entirely transparent and exhibit the sequence (100)–(301)–(101)–(001) in the development of the crystal faces. The mineral is highly yttrian with an atomic ratio yttrium/lanthanides = 78:22 and, in the relative abundance of the lanthanides, shows a strongly pronounced maximum of gadolinium. X-ray and optical data and density are given.