Arkansas

There are three alkaline intrusions in Arkansas, that I will deal with on these pages. I first tried to put them on one page, but you would have gotten a lame arm from scrolling through three pretty long mineral lists.

I would like to thank László Horvath and J.Michael Howard for information and the latter for specimens, too. Thanks also to Peter G.Seroka for information and the Woolley book.

To go to the localities:

Magnet Cove

Potash Sulphur Springs (aka Wilson Springs mines)

Granite Mountain

Further Arkansas localities:

Perry and Conway Counties: Sills, dykes, plugs. Shonkinite, syenite, aegirine-granite. Aegirine, amphibole grp., analcime, biotite, melanite, nepheline, pyroxene grp.

Montgomery County. Carbonatite, very small.

„V“ Intrusive: Complex dyke system. Malignite, melteigite, ijolite, syenites, pulaskite. Fluorite, pyrite.

Little Rock: Extension of Granite Mt., probably 50x30km, which would be North America´s largest intrusion. Nepheline syenties. Aegirine, amphibole grp., analcime, biotite, feldspar grp., nepheline, pyroxene grp., sodalite.

Saline Co.: Probably outcrop of Little Rock intrusion. Nepheline syenites, tinguaite, monchiquite, overlying bauxite deposits (mining). Aegirine, aegirine-augite, analcime, arfvedsonite, astropyhllite, biotite, diopside, nepheline, perthite, plagioclase, sodalite.

Prairie Creek (plus Kimberlite Mine, American Mine, Black Lick): 700m in diameter. Lamproite, breccia tuff, mica peridotite. Amphibole grp., clinopyroxene, diopside, olivine, perovskite, phlogopite, priderite, richterite. Exploited commercially for diamonds !

&Suggested reading:

Woolley, A.R.: Alkaline Rocks and Carbonatites of the World. Part 1: North and South America. British Museum (Natural History), London, 1987

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