One of the rocks that has been studied as a potential source of K is the volcanic phonolite
found in Pocos de Caldas, MG, Brazil, which presents 8.0% of total [K.sub.2]O.
are characterized by phenocrysts of leucite-pseudomorphs, alkali feldspar ([Or.sub.47-75]), clinopyroxene ([Wo.sub.48-50][Fs.sub.11-34]), Fe-pargasite, and nepheline [+ or -] biotite [+ or -] titanite [+ or -] melanite (Ti-andradite up to 68 wt%) [+ or -] magnetite or haematite.
Andreas also had nice little specimens of tuperssuatsiaite from the Aris Phonolite
; lovely deep green Erongo Mountains fluorite across a range of sizes; a couple of the elusive grossular crystals from Marienfluss, and many other Namibia goodies.
The investigated screes are formed by andesite, basalt, conglomerate, limestone, phonolite
, quartzite, sandstone, granite and other kinds of rock.
Novak J.K., Melka K., Ulrych J., Randa Z.: Phonolite
Weathering Profiles at Marianske Hora Hill, Ceske Stredohori Mts., and Sorption Properties of Clay Residues
Similar position of the sodalite pheno-crysts has been reported from zeolitized phonolite
of the Marianska hora Hill (Ulrych et al., 2000).
1997 From alkali basalt to phonolite
in hand-sized samples: vapor-differentiation effects in the Bouzentes lava flow (Cantal, France).
The most intriguing of these was a find, this past summer, of gemmy orange villiaumite crystals from the Aris phonolite
The two groups are at odds about the striking 867-foot-high assemblage of igneous phonolite
porphyry that prompted Theodore Roosevelt to designate it the country's first national monument.
Some of the weathered phonolite
bodies, buried beneath the Most Basin and covered by Miocene sediments, have been studied in open cast lignite mines.
Three reference suites from Iceland, Moorea and Tristan da Cunha illustrate (respectively) the tholeiitic series containing basalt to rhyolite, the alkaline series with alkali basalts to trachytes and a strongly alkaline series, beginning with basanite and ultimately yielding phonolite
; few oceanic islands contain tholeiiteseries rocks.
Ninety species have been documented from the quarry, mostly from the unique, dawsonite-rich carbonatized phonolite
sills which are genetically part of the Monteregian Hills alkaline igneous province.