Eosphorite is a somewhat common secondary mineral. It forms from the alteration of primary granitic phosphates such as lithiophilite and triphylite when aluminum and water are available. Eosphorite has been made famous in the mineral collecting world by being an accessory to the wonderfully well formed crystals of rose quartz at Taquaral, Minas Gerais, Brazil.
Eosphorite forms a solid solution series with the mineral childrenite. Childrenite's formula is (Fe, Mn)AlPO4(OH)2 - H2O and differs from eosphorite by being rich in iron instead of manganese. The structures of the two minerals are the same and therefore it would be expected that their differences in physical properties between the two would be related to the iron/manganese percentage. Eosphorite is less dense and is generally pinkish to rose-red in color whereas childrenite's colors tends towards various shades of brown. In terms of crystal habits the two also differ. Eosphorite forms prismatic, slender crystals and rosettes. Childrenite forms tabular or bladed individuals or lamellar aggregates. It has been said that the two different habits belie their solid solution relationship.