The mineral Vivianite is a monoclinic phosphate with chemical formula Fe32+(PO4)2??H2O. It is a fragile mineral, occurring in the form of tabular, columnar or acicular (needle-like) crystals, sometimes as radial aggregates as seen in this sample. Fresh crystals are transparent and colorless, with a glassy luster, but under light they tend to darken into blue or dark green hues, often vivid and attractive. Vivianite most usually occurs in the oxidation zones of ore deposits. It may also form in sediments rich in shells or other organic remains, and is sometimes found inside fossils.Sample width is 300 mm, provenance unknown.