“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 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”.*
| 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.