Gjerdingselva (Gjerdingen), Nordmarka, Lunner, Oppland, Norway

The locality is located about 1 km east of the Lake Gjerdingen, and consists as small outcrops/roadcuts beside the dirtroad from Lake Gjerdingen, close to Gjerdingenelva (river), going to Stryken station. It is a part of the "ekerite" (a soda granite) rich in zirconium, titanium and fluorine; locally occuring as an "elpidite-ekerite" and very locally as a "janhaugite-elpidite-ekerite".

References:
- Sæbø, P. Chr. (1966): A short comment on some Norwegian mineral deposits within the Igneous Rock Complex of the Oslo Region. Norsk Geologisk Tidsskrift 46, 260-261

- Raade, G. (1972): Mineralogy of the miarolitic cavities in the plutonic rock of the Oslo Region. Mineralogical Record 3, 7-11.

- Raade, G. & Haug, J. (1980): Rare Fluorides from a soda granite in the Oslo Region, Norway. Mineralogical Record, 11, 83-91

- Raade, G. & Haug, J. (1981): Morphology and twinning of sellaite from Gjerdingen, Norway. Mineralogical Record 12, 231-232

- Eldjarn, K. (1981): Drusemineraler fra Gjerdingen i Nordmarka. NAGS-nytt 8 (2), 6-10 (in norwegian)

- Eldjarn, K. (1981): Kryolitt fra Gjerdingen i Nordmarka. NAGS-nytt 8 (2), 11-12 (in norwegian)

- Raade, G. & Haug, J. (1982): Gjerdingen. Fundstelle seltener Mineralien in Norwegen. LAPIS 7 (6), 9-15

- Raade, G. & Mladeck, M. H. (1983): Janhaugite,.. A new mineral from Norway. American Mineralogist 68, 1216-1219.

- Ljøstad, O.T. (1988): Doyleitt. NAGS-nytt 15 (1-4), 23

- Raade, G., Ferraris, G., Gula. A. & Ivaldi, G. (2002): Gjerdingenite-Fe from Norway, a new mineral species in the labuntsovite group: description, crystal structure and twinning. Canadian Mineralogist 40, 1629-1639

- Raade, G., Chukanov N.V., Kolitsch U., Möckel S., Zadov, A.E., Pekov I.V. (2004): Gjerdingenite-Mn from Norway - a new mineral species in the labuntsovite group: descriptive data and crystal structure. European Journal of Mineralogy, 16, 979-987.

- Raade, G. (2005): Gjerdingen-ekeritten, en unik mineralforekomst. [The Gjerdingen-ekerite, a unique minerallocality]. Bergverksmuseets Skrift (Norsk Bergverksmuseum) 30, 14-18.

- Raade, G. (2009): Plumbopyrochlore, ceriopyrochlore-(Ce), wulfenite and andradite from the Gjerdingen ekerite. Bergverksmuseets Skrift (Norsk Bergverksmuseum) 41, 25-30.

- http://www.koeln.netsurf.de/~w.steffens/gjerd.htm