Atoll Texture in Minerals of the Cobaltite-Gersdorffite Series from the Raipas Mine, Finnmark, Norway
Particularly fine examples of “atoll-texture” are shown by Co-Ni-Fe-(Cu) sulpharsenides in specimens from the disused Raipas mine near Alta, Finnmark, northern Norway. Reinvestigations by optical, electron microprobe, and X-ray diffraction techniques have shown that the atolls, and the grains from which they appear to have developed by core replacement, are composed of two mineral phases. One, with a general composition (Co,Ni,Fe,Cu)3As2S4 can be shown to be a Co-rich member of the cobaltite-gersdorffite series; the other phase, (Co,Ni,Fe,Cu)2AsS2, does not appear to correspond to any reported natural mineral having this general composition.
The nature of the often spheroidal grains from which the atolls have developed is not too certain. They bear certain resemblances to the general class of framboidal textures, though their compositions and internal structures are unusual.
KeywordsCobalt Uranium Shale Dolomite Pyrite
Unable to display preview. Download preview PDF.
- Edwards AB (1954) Textures of the ore minerals and their significance. Inst Min Metall, Melbourne, Australia, 242 ppGoogle Scholar
- Klemm DD, Weiser T (1965) Hochtemperierte Glanzkobalt-Gersdorffit-Mischkristalle von Outokumpu/Finnland. Neues Jahrb Mineral Monatsh 1965:236–241Google Scholar
- Krause H (1965) Idaite, Cu5FeS6 from Konnerud, near Drammen. Contributions to the mineralogy of Norway, no 33. Nor Geol Tidsskr 45:417–422Google Scholar
- Love LG (1964) Early diagenetic pyrite in fine-grained sediments and the genesis of sulphide ores. In: Amstutz GC (ed) Developments in sedimentology, vol II, Sedimentology and ore genesis. Elsevier, Amsterdam, pp 11–17Google Scholar
- Neumann H (1944) Silver deposits at Kongsberg. Nor Geol Unders Publ 162:133Google Scholar
- Petruk W (1971) Mineralogical characteristics of the deposits and textures of the ore minerals. Can Mineral 11:108–139Google Scholar
- Petruk W, Harris DC, Stewart JM (1971) Characteristics of the arsenides, sulpharsenides and antimonides. Can Mineral 11:150–186Google Scholar
- Ramdohr P (1969) The ore minerals and their intergrowths. Pergamon Press, Oxford, 1124 ppGoogle Scholar
- Rosner B (1970) Mikrosonden-Untersuchungen an natürlichen Gersdorfflten. Neues Jahrb Mineral Monatsh 1970:483–498Google Scholar
- Schouten C (1937) Metasomatische Probleme, Amsterdam (quoted in Edwards 1954)Google Scholar
- Vokes FM (1955) Observations at Raipas Mine, Alta, Finnmark. Nor Geol Unders Publ 191 (Årbok 1954):103–114Google Scholar
- Vokes FM (1957a) Some copper parageneses from the Raipas formation of northern Norway. Nor Geol Unders Publ 200 (Årbok 1956):74–111Google Scholar
- Vokes FM (1957b) On the presence of minerals of the linnaeite series in some copper ores from the Raipas formation of northern Norway. Nor Geol Unders Publ 200 (Årbok 1956):112–120Google Scholar