Vivianite

Vivianite is a hydrated iron phosphate that belongs to the vivianite group of minerals. Vivianite has vibrant colours such as blue, green and colourless with a vitreous lustre.
Many clusters are found inside of fossil, clam or snail shells or attached to fossil animal bone. Vivianite is transparent to translucent and occurs as radiating clusters of prismatic, acicular, or fibrous crystals, also earthy and encrusting masses.