- Supergene: post-mining oxidation & weathering deposits
- Supergene: in situ natural oxidation & weathering deposits
- Ystrad Einion Mine, Furnace, Ceredigion: several crystal forms have been observed. All are relatively rare, derived from low-grade sulphide ore dominated by chalcopyrite, with minor galena and sphalerite, in a quartz gangue containing ferroan dolomite which has reacted with mine water in a short backfilled passage. Sulphides have dissolved and secondary minerals precipitated out within cavities in corroded ferroan dolomite. Parallel groups of thin, pale, emerald-green bladed crystals to about 3 mm in association with serpierite and gypsum have been identified at Oxford University Museum and a more typical tabular crystal form has been identified at the Natural History Museum, London. Further to this corroded lenticular crystals to 0.7 mm on joints in silty sandstone have also been identified as ktenasite (Mason & Rust, 1997).
There are no key localities for this specimen.
- Bevins, R.E., 1994. A Mineralogy of Wales National Museum of Wales, Geological Series No. 16, Cardiff, 146pp.
- Mason, J.S. & Rust, S.A., 1997. The Mineralogy of Ystrad Einion Mine, Dyfed, Wales. U.K. Journal of Mines and Minerals, 18, 33-36.
There are no references for this specimen.