WAVELLITE  , a

mineral consisting of hydrated aluminium phosphate, A13(OH)3(PO4)2 + 4aH2O, crystallizing in the orthorhombic system . Distinct crystals are of rare occurrence, the mineral usually taking the form of hemispherical or globular aggregates with an internal radiated structure . It is translucent and varies in colour from grey or white to greenish, yellowish, &c . The hardness is 31f and the specific gravity 2.32 . It was first found, at the end of the 18th century, by Dr W . Wavell near Barnstaple in Devonshire, where it lines crevices in a black slaty rock . It has also been found in Ireland (Tipperary and Cork), Arkansas, &c . (L . J .