Ref.: Halkoaho, T.A.A. (1993) The Sompujärvi and Ala-Penikka PGE reefs in the Penikat layered intrusion, northern Finland: implications for PGE reef-forming processes. Acta Univ. Oul. A249, University of Oulu, Oulu, Finland.
http://www.gsf.fi/explor/pgeweb/penikat/alapenikka.htm21 entries listed. 19 valid minerals.