Point of Rocks
Thanks to Peter G.Seroka for the information.
Point of Rocks is a Mesa 15km E of Springer on I-25 in NE New Mexico. It is a phonolite sill, consisting of alkali feldspar, zeolites and nepheline, which caps a mesa of olivine basalts and certaceous sedimentary rocks.
Mineral list: (probably incomplete):
Thanks to László Horváth and Peter G.Seroka for providing me with the literature, to Chris Grohusko for the Wind Mt.foto, and especially to Prof.Dr.Wolfgang Stoll for information and the fantastic micro fotos !
There is a second alkaline locality
in New Mexico, which is much lesser known and more difficult to access:
Wind Mountain is one of several (about 20) intrusive bodies of syenite, nepheline syenite, phonolite and trachyte, hornfels, too, in the Cornudas Mts. in southern Otero County in New Mexico close to the NM/Texas border, part of the Cornubas Mts./Diablo Plateau complex. They were emplaced in the Eocene as sheets, sills and laccolites in sediments. Namely W.M. is a nepheline syenite with miarolitic cavities.
Obviously there are just blocks on the mountain slope from which to collect, and it shall be difficult to find unweathered blocks with vugs.
Fotos of the mountains courtesy of Chris Grohusko left Wind Mt., reight Cornubas Mts.
Mineral Fotos courtesy of Prof.Dr.Wolfgang Stoll, Hanau, Germany
Mineral list for Wind Mt. (bold=type locality, italics=variety):
Mineral list for Cornubas Mts./Diablo
Boggs,R.C., S.Ghose: Georgechaoite, a new mineral species from Wind Mountain, New Mexico, Can.Mineralogist 23(1985), pp.1-4
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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