CHILDRENITE, a rare mineral species; a hydrous basic aluminium iron phosphate, orthorhombic in crystallization. The ferrous oxide is in part replaced by manganous oxide and lime, and in the closely allied and isomorphous species eosphorite manganese predominates over iron. The general formula for the two species is Al(Fe, Mn)(OH) PO  + H O. Childrenite is found only as small brilliant crystals of a yellowish-brown colour, somewhat resembling chalybite in general appearance. They are usually pyramidal in habit, often having the form of double six-sided pyramids with the triangular faces deeply striated parallel to their shorter edges. Hardness 4.5-5; specific gravity 3.18-3.24. The mineral, named after the zoologist and mineralogist J.G. Children (1777-1852), secretary of the Royal Society, was detected in 1823 on specimens obtained some years previously during the cutting of a canal near Tavistock in Devonshire. It has also been found in a few copper mines in Cornwall and Devonshire.
Eosphorite occurs as crystals of prismatic habit with angles very nearly the same as those of childrenite. Unlike childrenite, it has a distinct cleavage in one direction, and often occurs in compact masses as well as in crystals. The colour is sometimes yellowish-white, but usually rose-pink, and on this account the mineral was named from , dawn-bearer. Hardness 5; specific gravity 3.11-3.145. It was discovered in 1878 in a pegmatite-vein at Branchville, Connecticut, where it is associated with other rare manganese phosphates.
(L. J. S.)
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)