Informations are from H.J.Wilke´s great new book on Sweden.
Alnö is an island on the east coast of Sweden, that is in the Baltic Sea, not far from Sundsvall. Here a migmatic greisgranite has been intruded - among other rock types - by alkaline rocks. These even alkalized the bed rock. There are several intrusions - a main one with two areas and several smaller ones. The northern part of the main intrusion has a wide surronding breccia-zone including carbonatites, the southern part of it has a large fenite zone around it. The island is extremely famous for geologists as there are lots of rock types known only from this locality (melteigite, ijolite, urtite, borengite, alnoeite). All in all the geology is extremely complicated. On the mainland there are even kimberlites.
Mostly the minerals of the different rock types occurs as nothing more than fine to coarse grained rock forming minerals. There are hardly any pegmatites at all, just a few pegmatite-like rocks (melteigite, ijolite, urtite). The rocks richest in minerals are the carbonatites. However, of the many minerals described from here, quite a lot are just rock-forming, or visible only by special techniques (polarization or ore microscopy). And..... no eudialyte anyhow !!
Personally I have never been there, and I see few chances to do so, as from Germany it is quite far off.
H.J.Wilke:Die Mineralien und Fundstellen von Schweden, Christian Weise Verlag, München, 1997, S.136-140
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