Field observations and the geochemistry of major and trace elements, including REE, suggest a mafic extrusive origin for the strongly tectonized, actinolitealbite rocks in the Miihkali arch, in the NE part of the Outokumpu district, eastern Finland. These metabasalts occur in close association with massive serpentinites. Compared with the average composition of representative basalts from modern tectonic environments their MgO, Ni and Cr contents are somewhat elevated, and their Ti0 2 somewhat low. The REE contents are 5x to 10 x chondrites. Their pattern is flat and slightly depleted in LREE. A Proterozoic ocean floor is postulated as the depositional environment.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.