Aris


Special thanks to Ralf Wartha in Windhoek, Namibia, for specimens and informations and to László Horváth for the mineral list and geological informations.
I also do owe a lot of thank to Laurence A. J. Garvie -
lgarvie@asu.edu -, who is doing research at the Arizona Sstate University at Tempe,AZ on the mineralogy of Aris.
Also to be mentioned is Dr.Uwe Kolitsch -
http://www.univie.ac.at/mineralogie/kolitsch.htm from Vienna University, who is also doing research on Aris, and who just (11/00) identified the very rare wurtzite-15R polytype from there.


The mineralogy of this locality is currently studied in some more detail in a collaborative effort by Dr. Garvie and Dr. Kolitsch. It is planned to publish the results in a comprehensive article, probably in the Mineralogical Record. Collectors with unidentified minerals from Aris are encouraged to contact one of these mineralogists.


Aris is a phonolite quarry about 20 km S of Windhoek, Namibia, which is mined (on and off) for road gravel. This phonolite is one of many phonolites belonging to several alkaline intrusions between Windhoek and Rehoboth in central Namibia. These intrusions are the latest manifestations of tertiary alkaline magmatism along the western margin of southern Africa, as are the phonolites at Klinghardt Mountains SE of Luederitz. The phonolites occur as flows, dykes and plugs exposed as eroded outcroppings and caps on small hills and buttes.
Some zones of the phonolite rock contain numerous small cavities, mostly 1-2 cm in diameter with exceptional cavities to about 8 cm, with well-formed, microscopic crystals of various minerals. Most famous is the abundant occurrence of the world´s best tuperssuatsiaite, but well-crystallised villiaumite and makatite should be mentioned, too.
The mineral list probably is incomplete - I still got the unknowns from Ralf Wartha to take fotos of them and have them analyzed. So there´s more to come....

Mineral list:


Aegirine
Aenigmatite
Analcime
Na-Apophyllite
Aragonite
Arisite“ - intergrown w/tup.
Barite
Bastnaesite-(Ce)
Biotite
Calcite
Canasite ?
Cancrinite
Cryolite ?

Eudialyte
Ferropargasite
Fluorapatite
Fluorapophyllite
Fluorite
Galena
Hydroxylapatite
Hydroxylapohyllite ?
Iraqite-(La) wrong: this is sazhinite
Kaersutite
Kanemite
Korobitsynite
Lanthanite-(Ce)
Lovozerite
Magadiite
Magnesio-aluminokatophorite ?
Magnetite
Makatite
Mangan-Neptunite
Microcline
Monazite-(Ce)
Muscovite
Natrolite
Natrophosphate
Nenadkevichite ?
Nepheline
Polylithionite
Rhodochrosite ?
Sanidine
Sazhinite-(Ce) ? - if it's not all -(La)

Sazhinite-(La)
Sodalite
Sphalerite
Tetranatrolite ?
Titanite
Tuperssuatsiaite
Villiaumite
Wurtzite
„Fe-Zakharovite“
Zircon
Mt.St.Hilaire UK 77

 

 

 

 

 

 

 

 

 

 

 

 &Suggested reading:

Camara,F et al.: The structure of Mn-rich tuperssuatsiaite: a palygorskite-related mineral. AMERICAN MINERALOGIST, 87(2002), 1458-1463

Garvie,LAJ et al.: Crystal structure of kanemite, NaHSi2O5*3H2O, from the Aris phonolite, Namibia. AMERICAN MINERALOGIST, 84(1999), 1170-5


Marsh, J.S. (1987) Evolution of a strongly differentiated suite of phonolites from the Klinghardt Mountains, Namibia. Lithos, 20(1987), pp.41-58


Niedermayr,G et al.: Korobitsynite from the Aris phonolites, Windhoek, Namibia. NEUES JAHRBUCH FÜR MINERALOGIE-MONATSHEFTE, 1/2002, 42-48. Colourless, tansparent, prismatic crystals to 1mm, as individuals or in sprays scattered on platy albite and analcime crusts.

Petersen, O.V., Fockenberg, T., Toft, P.C. & Rattay, M. (1997): Natrophosphate from the Aris phonolites, Windhoek, Namibia. Neues Jahrbuch für Mineralogie, Monatshefte 1997, 511-517


von Knorring,O, W.Franke: A preliminary report on the mineralogy and geochemistry of the Aris phonolite, SWA/Namibia. Communications of the Geological Survey of S.W. Africa/Namibia, 3(1987), p-61.


Von Knorring,O., O.V.Petersen, S.Karup-Moeller, E.S.Leonardsen, E.Condliffe: Tuperssuatsiaite, from Aris phonolite, Windhoek, Namibia. Neues Jahrbuch für Mineralogie, (1992), 145-152

Camara F et al.: Sazhinite-(La), Na3LaSi6O15(H2O)2, a new mineral from the Aris phonolite, Namibia: description and crystal structure.MINERALOGICAL MAGAZINE, 70(2006), 405-418

New mineral: euhedral xx to 1x0.4mm, good cleavage, brittel hardness3, creamy white with white streak, vitreous to pearly luster, translucent to transparent. w/atrolite, aegirine, microcline, apophyllite, sphalerite, analcime, fluorite, villiaumite, hydroxylapatite, galena, makatite, quartz, eudialyte, kanemite, tuperssuatsiaite and korobitsynite.

 

 


There is more literature, but it´s either old (1933) or difficult to obtain.


Back to main page.