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Mineral Environments
- Miarolitic Cavities -

     "Small, generally spherical miarolitic cavities rarely exceeding 10 cm in diameter, in nepheline syenite, are the mode of occurrence for a unique mineral assemblage rich in rare earth silicates and carbonates. The nepheline syenite is a dense, medium to dark gray rock, relatively uniform in color, texture and mineralogy."

Miarolitic cavity - click for larger pic
Miarolitic cavity from MSH
© Quintin Wight


     "The miarolitic cavities are not uniformly distributed throughout the nepheline syenite, but tend to be concentrated in some areas while other areas are completely devoid of them. The reason for this localization is not well understood. The cavities are characteristically lined with a thin layer of foliated biotite and analcime on which the other minerals occur".*

Minerals found in miarolitic cavities
Aegirine
Albite
Analcime
Anatase
Ancylite-(Ce)
Andradite
Aragonite
Arsenopyrite
Ashcroftine-(Y)
Astrophyllite
Barite
Barylite
Bastnäsite-(Ce)
Behoite
Biotite
Brookite
Burbankite
Calcite
Catapleiite
Donnayite-(Y)
Edingtonite
Elpidite

Eudialyte
Ewaldite
Fluorapatite
Fluorite
Franconite
Gaidonnayite
Galena
Gibbsite
Gonnard
Harmotome
Hematite
Hilairite
Hochelagaite
Ilmenite
Labuntsovite
Magnetite
Microcline
Molybdenite
Monteregianite-(Y)
Natrolite
Nepheline
Paranatrolite
Parisite-(Ce)
Phillipsite
Pyrite
Pyrophanite
Pyrrhotite
Rinkite
Rosenbuschite
Rutile
Sanidine
Scheelite
Siderite
Sodalite
Sphalerite
Synchysite-(Ce)
Thomsonite
Titanite
Vinogradovite
Wöhlerite
Xenotime-(Y)
Zircon

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