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Mineral Environments
- Altered Pegmatites -

     "The pegmatites, which are the residual portion of the magma and the last to have crystallized, can take the form of dikes, pipes and lenses. They appear to have no continuation at depth. Many of them pinch and swell irregularly from a few centimeters to a meter or more in width. Where the pegmatites swell, open cavities occur with well formed crystals growing in the cores. Included under pegmatites are small, coarse grained patches and segregations in nepheline syenite".*

     "The syenitic pegmatites of MSH generally are rich in sodium silicates and rare element minerals" (Table a - Unaltered pegmatites). "The most common minerals of the pegmatites are microcline and aegirine with local concentration of analcime, sérandite and catapleiite. Many of the pegmatites are altered in varying degrees, probably by hydrothermal action. These are characterized by manganese oxides, chlorites, sulfides and other minerals" (Table b - Altered pegmatites).*

Table b - Minerals found in altered pegmatites
Aegirine
Albite
Analcime
Anatase
Ancylite-(Ce)
Anglesite
Ankerite
Arfvedsonite
Arsenopyrite
Astrophyllite
Bastnäsite-Ce)
Behoite
Berthierine
Beudantite
Biotite
Birnessite
Brockite
Burbankite
Calcite
Carbonate-fluorapatite
Catapleiite
Celestine
Cerussite
Chabazite
Chalcopyrite
Cordylite-(Ce)
Daqinshanite-(Ce)
Datolite
Donnayite-(Y)
Doyleite
Elpidite
Epididymite
Eudialyte
Eudidymite
Fluorapatite
Fluorite
Gaidonnayite
Galena
Genthelvite
Gibbsite
Goethite
Gonnardite
Gypsum
Halotrichite
Helvite
Hemimorphite
Hilairite
Hisingerite
Hochelagaite
Hydrocerussite
Hydrozincite
Jarosite
Kupletskite
Kutnohorite
Låvenite
Lemoynite
Lepidocrocite
Lizardite
Löllingite
Magnesioarfvedsonite
Marcasite
Mckelveyite-(Y)
Microcline
Mimetite
Monazite-(Ce)
Muscovite
Natrolite
Nenadkevichite
Neotocite
Nordstrandite
Paranatrolite
Paraumbite
Parisite-(Ce)
Petarasite
Polylithionite
Pyrite
Pyrochlore
Pyrophanite
Pyrrhotite
Quartz
Rhabdophane-(Ce)
Rhodochrosite
Rinkite
Rutile
Sabinaite
Sérandite
Siderite
Sodalite
Sphalerite
Synchysite-(Ce)
Szomolnolkite
Thaumasite
Thornasite
Titanite
Weloganite
Wulfenite
Yofortierite
Zircon

* From Mineralogical Record Vol 21, Horváth L. and Gault R.A.