Properties
| Category | Phosphate mineral ; Vivianite group |
|---|---|
| Formula | Fe2+; 3(PO; 4); 2·8H; 2O |
| Crystal system | Monoclinic |
| Color | Colorless, very pale green, becoming dark blue, dark greenish blue, indigo-blue, then black with oxidation |
| Crystal habit | Flattened, elongated prismatic crystals, may be rounded or corroded; as stellate groups, incrustations, concretionary, earthy or powdery |
| Cleavage | Perfect on {010} |
| Fracture | Fibrous |
| Tenacity | Flexible, sectile |
| Mohs scale hardness | 1.5–2 |
| Luster | Vitreous, pearly on the cleavage, dull when earthy |
| Streak | White, altering to dark blue, brown |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 2.68 |
From the Wikipedia article
Vivianite (Fe(II)3(PO4)2·8H2O) is a hydrated iron(II) phosphate mineral found in a number of geological environments. Small amounts of manganese Mn2+, magnesium Mg2+, and calcium Ca2+ may substitute for iron Fe2+ in its structure. Pure vivianite is colorless, but the mineral oxidizes very easily, changing the color, and it is usually found as deep blue to deep bluish green prismatic to flattened crystals. Vivianite crystals are often found inside fossil shells, such as those of bivalves and gastropods, or attached to fossil bone. Vivianite can also appear on the iron coffins or on the corpses of humans as a result of a chemical reaction of the decomposing body with the iron enclosure.
Source
Source record: crystal-compendium/vivianite/minerals.json. Fetched from English Wikipedia by the operator 2 October 2026.
https://en.wikipedia.org/wiki/Vivianite — revision id 1377480116. Text and properties from Wikipedia, licensed CC BY-SA 4.0.