A secondary mineral, with the formula Al3(PO4)2(OH)3. 5H2O; sp. gr. 2.3–2.4; hardness 3.5–4.0; orthorhombic; normally white, but often greenish, yellow, grey, or brown; vitreous lustre; normally forms fibrous, radiating aggregates, or hemispherical or globular aggregates; found on joint surfaces and cavities in rock, especially slates and shales, and in association with limonitic orebodies. It is named after the 18th-century British mineralogist W. Wavell, who discovered it.