Blue-green crystals of vivianite, partly altered to goethite and other minerals. Oxon Hill, Prince Georges County, Maryland . Field of view about 1 cm left to right. (Photo by W. Cordua.)
Formula: Fe3(PO4)2.8H2O Monoclinic
Description: Vivianite is an iron phosphate mineral found in bladed crystals and clusters of an intense blue to green color. It can form in a variety of environments such as a sedimentary precipitate or in hydrothermal veins.
RUSK COUNTY: Bladed clusters of tiny crystals of a deep green color were found in the oxidized zone of the Flambeau Copper Mine, near Ladysmith. (Buchholz, pers. com.)
Properties of minerals 