"Rock of the Month # 297, posted for March 2026" ---

Wavellite

is an aluminium phosphate, ideal formula Al₃[(OH)₃(PO₄)₂].5H₂O. It has orthorhombic symmetry and often displays an acicular habit in radiating spheroidal aggregates. See Wavellite from England for a detailed description of the phosphate and its worldwide occurrence. Apparently there is some systematic debate over the definition of the mineral, which puts the type locality of High Down quarry (S.W. England) into some doubt (see Tindle and Green, 2024, reviewed by Patrick Roycroft in Elements 21 no.6, pp.454-455, December 2025).

Ballybunnion is situated on the Atlantic coast, just south of the Shannon estuary in northwest Kerry, west of Limerick and northwest of Listowel. In this part of the west of Ireland there are thick sequences of sedimentary rocks of Carboniferous age, preserved in the Shannon basin (Holland, 2001, pp.255-258, 262, 275, 294, 296, 298, 323). These strata include much fine-grained limestone (micrite) and coarser, sparry calcite, a range of fossil assemblages, and shale. Phosphates occur in the Clare Shale Formation (ibid., p.294). Lithological controls influence the extensive folding styles evident in the regional strata (ibid., p.323).

REFERENCES

Holland,CH (editor) (2001) The Geology of Ireland. Dunedin Academic Press, Edinburgh, 531pp.

Tindle,AG and Green,DI (2024) Minerals of Britain and Ireland, 2009-2024. Independent Publishing Network / Russell Society, 400pp.