Mineralium Deposita

, Volume 24, Issue 2, pp 117–123

Genesis of coffinite and the U-Ti association in lower old red sandstone sediments, Ousdale, Caithness, Scotland

  • C. M. Pointer
  • J. R. Ashworth
  • P. R. Simpson

DOI: 10.1007/BF00206313

Cite this article as:
Pointer, C.M., Ashworth, J.R. & Simpson, P.R. Mineral. Deposita (1989) 24: 117. doi:10.1007/BF00206313


The mineralogy of a fault-related uranium occurrence, in clastic rocks overlying granite, is described from borehole material. Coffinite is the only important uranium mineral. Other notable minerals are sulphides, fluorite, calcite and hydrocarbon. Coffinite is epigenetic and paragenetically late, rimming sulphides and hycrocarbon. It occurs partly in spatial association with a TiO2 mineral (probably anatase). This U-Ti association is attributed to adsorption of U by altered Ti-minerals prior to growth of the U mineral. Thus is has similarities with many diagenetic occurrences, though their mineralogy is usually different (the U-Ti association being represented by uranotitanates). The latter are attributed to local supersaturation of TiO2, which did not occur at Ousdale because Ti was relatively mobile in the fluids. Coffinite + TiO2 + quartz is interpreted as a stable low-temperature assemblage. The mineralogy thus indicates a hydrothermal uranium mineralization of an unusual type (without prominent uraninte), formed from relatively low-temperature fluids containing complexing agents which mobilized Ti.

Copyright information

© Springer-Verlag 1989

Authors and Affiliations

  • C. M. Pointer
    • 1
  • J. R. Ashworth
    • 2
  • P. R. Simpson
    • 3
  1. 1.Department of ChemistryAberdeen UniversityOld AberdeenU.K.
  2. 2.School of Earth SciencesUniversity of BirminghamBirminghamU.K.
  3. 3.Geochemistry and Hydrogeology DirectorateBritish Geological SurveyLondonU.K.