Green Vivianite Crystal | Brazil
7.2g 3.5" x .5" at widest part
Vivianite is a hydrous iron phosphate mineral that is completely clear until exposed to light. After exposure, the iron oxidizes, and the crystal begins to darken. If exposed long enough, a specimen may turn black and opaque. Manganese, magnesium, or calcium may substitute the iron. Vivianite usually appears in prismatic or flattened crystals that are deep blue or bluish green in color.
The highest quality of vivianite usually comes from hydrothermal veins. However, vivianite can be found inside fossil shells, such as bivalves and gastropods. Vivianite has even been found attached to fossil bones.
*Sensitive to light.