Alnö

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.

Mineral list:

Aegirine
Aegirine-augite
Aeschynite-(Ce)
Akermanite
Albite
Allanite-(Ce)
Almandine
Analcime
Ankerite
Anorthoclase
Aphthitalite
Aragonite
Arsenopyrite
Baddeleyite
Barite
Biotite
Bravoite
Britholite-(Ce)
Brockite
Brucite
Calcite
Calzirtite
Cancrinite
Carbonatehydroxylapatite
Celestite
Cerianite
Chalcopyrite
Chlorite
Chromite
Columbite
Corundum
Diamond
Diopside
Dolomite
Dysanalyte
Edenite
Enstatite
Epidote
Ferrohornblende
Fersmite
Fluorite
Fluoroapatite
Fluoroapophyllite
Forsterite
Galena
Gehlenite
Gersdorffite
Goethite
Graphite
Gypsum
Halite
Hanksite
Harmotome
Hastingsite
Hauyne
Hedenbergite
Hematite
Hornblende
Illite
Ilmenite
Kalicinite
Kimzeyite
Kyanite
Mackinawite
Maghemite
Magnesioarfvedsonite
Magnetite/Titanomagnetite
Marcasite
Melanite
Melilite
Molybdenite
Monazite-(Ce)
Monticellite
Muscovite
Nahcolite
Natrolite
Nepheline
Noseane
Olivine
Orthoclase
Pargasite
PEctolite
Pentlandite
Periclase
Perowskite
Phlogopite
Pigeonite
Prehnite
Pyrite
Pyrochlore
Pyrope
Pyrophanite
Pyrrhotite
Richterite
Scheelite
Schorl
Schorlomite
„Serpentine“
Sillimanite
Spahlerite
Spesssartine
Spinell
Staurolite
Strontianite
Sylvite
Synchisite-(Ce)
Talc
Tazheranite
Thenardite
Thomsonite
Thorite
Titanaugite
Titanite
Valleriite
Violarite
Vivianite
Wollastonite
Xonotlite
Zircon

Zirconolite


&Suggested reading:

H.J.Wilke:Die Mineralien und Fundstellen von Schweden, Christian Weise Verlag, München, 1997, S.136-140


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