Skjærpemyr mines are the most interesting and richest mines in the Grua District.
The area is protected by law and it is not allowed to collect pieces from rock. Hammering and digging is strictly forbidden.
Ref:
-Goldschmidt, V.M. (1911): Die Kontaktmetamorphose im Kristianiagebiet . Videnskapsselskapets Skrifter. 1.Mat.-Naturv. Klasse 1911. No 1. Kristiania (in german)
- Folvik, H. (2005): Mineralene på Skjerpemyr. STEIN 32 (1), 4-9 (in norwegian)
-Raade, G.(1995): Secondary Zn and Cu minerals from contact deposits of the Oslo region, Norway. Bergverksmuseet Skrift nr 9, 18-26
