Uraninite, chalcocite, bornite and chalcopyrite. Gortdrum, Ireland

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Rhythmically banded uraninite (light grey, centre) is extensively replaced by bornite (pink, centre left) and blue-white copper sulphide, chalcocite (centre bottom). The replacement has proceeded along radiating fractures and selected growth bands within the uraninite (centre). Silicate (bottom right) shows light coloured internal reflections and carries small intergrown chalcopyrite bornite (orange-yellow, bottom right) inclusions.

Polished block, plane polarized light, x 180, oil

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