A grandidierite-borosilite bearing abyssal pegmatite in the Rogaland anorthosite complex intruded in high-grade granulites. It occurs as a discordant, nearly vertical vein 10 m long and 10 cm wide hosted in pelitic rocks (gneises containing garnet, cordierite spinel, sillimanite) resulting from metamorphism under granulite-facies condition (Grew et al. 1998).
The host rocks:
Almandine migmatites (partially melted metapelites) within granulites at the contact of intrusive anorthosites (Bjerkrem-Sokndal layered lopolith) show hercynite-quartz and osumilite high-grade assemblages (750 °C-4 kb, up to 1050 °C at the anorthosite contact).
References:
- Waters, D. J. (1991): Hercynite-quartz granulites; phase relations, and implications for crustal processes. European Journal of Mineralogy
3: 367-386.
- Grew, E.S., McGee, J.J., Yates, M.G., Peacor, D.R., Rouse, R.C., Huijsmans, J.P.P., Shearer, C.K., Wiedenbeck, M., Thost, D.E., and Su, S.-C. (1998): Boralsilite (Al16B6Si2O37): A new mineral related to sillimanite from pegmatites in granulite-facies rocks. American Mineralogist: 83: 638-651
- Grew, E. S.; Yates, M. G. ; Huijsmans, J. P. P. ; McGee, J. J.; Shearer, C. K.; Wiedenbeck, M. & Rouse, R. C. (1998): Werdingite, a borosilicate new to granitic pegmatites, The Canadian Mineralogist 36, 399-414
- Kristiansen, R. (2000): Nytt om mineraler. Borasilite-Al16B6Si2O37- et nytt mineral fra Antarktis og Norge ! Stein 27 (1): 33
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Map Reference: 58°33'N , 6°31'E
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Mineral List:24 entries listed. 16 valid minerals.
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