Amorphous post-mining matter with the simplified formula CuAl₅(PO₄,SiO₄,SO₄,AsO₄)F(OH)_{11 – 13}·nH₂O (n = 5 – 6) was discovered in the West Caradon Mine, Liskeard District, Cornwall, England and characterized by means of electron microprobe analyses, direct determination of H₂O, IR spectroscopy, powder X-ray diffraction and optical data. Origin of the Cu-Al hydroxyphosphate and its relationships with amorphous phosphate minerals are discussed.