Crystal System: Tetragonal
Status of Occurrence: Confirmed Occurrence
Chemical Composition: Manganese oxide
Chemical Formula: Mn2+Mn3+2O4
Method(s) of Verification: Benallt Mine - XRD (Natural History Museum, X-ray nos. x3430, x3520, x3521 & x3542); Tŷ Coch - XRD (Natural History Museum, X-ray nos. x16374, x18242 & 5006F).
- Oxides & Hydroxides
Radiating hausmannite/braunite crystals in manganocalcite from T? Coch, near Porthcawl, South Wales. National Museum of Wales specimen (NMW 87.73G.M31), © National Museum of Wales.
Introduction: hausmannite occurs as a primary mineral in manganese-rich hydrothermal veins and within metamorphosed manganese deposits.
Occurrence in Wales: two confirmed occurrences of hausmannite are recorded from Wales. As with many manganese minerals visual identification is difficult.
- Benallt Mine, Llŷn, Gwynedd: hausmannite is a component of manganese ore at this locality. Natural History Museum specimen, B.M. 1945,133 contains hausmannite, as brown, iridescent plates associated with altered pyrochroite.
- Tŷ Coch, near Porthcawl, South Wales: hausmannite has been identified (Criddle & Symes, 1977) in manganese ore at the disused mine at Tŷ Coch, where it forms: i) euhedral to subhedral grains intimately associated with braunite, and interstitial an vug-filling calcite, manganoan calcite, ferroan calcite, dolomite, barite, minor pyrobelonite and vanadinite; and ii) euhedral crystal clusters associated with brown calcite interlayered with goethite and romanèchite.
- Criddle, A.J., & Symes, R.F., 1977. Mineralization at Tŷ Coch, Glamorgan (Mid Glamorgan), Wales: the second occurrence of pyrobelonite. Mineralogical Magazine, 41, 85-90.