Vivianite
| Colour | Blue, Green, Clear, Black |
|---|---|
| Mohs hardness | 1.5–2 |
| Lustre | Vitreous, pearly on the cleavage, dull when earthy |
| Streak | White, altering to dark blue, brown |
| Crystal system | Monoclinic |
| Transparency | Transparent to translucent |
| Cleavage | Perfect on {010} |
| Fracture | Fibrous |
| Specific gravity | 2.68 |
What is Vivianite?
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
How to identify Vivianite
- Lustre: Vitreous, pearly on the cleavage, dull when earthy.
- Hardness: Mohs 1.5–2 — soft; a knife will scratch it.
- Streak: White, altering to dark blue, brown.
- Habit: Monoclinic crystal system.
Vivianite in different forms
Stones often confused with Vivianite
Frequently asked questions
How hard is Vivianite?
Vivianite is Mohs 1.5–2 on the hardness scale.
What colour is Vivianite?
Vivianite is typically blue, green, clear, black (Colorless, very pale green, becoming dark blue, dark greenish blue, indigo-blue, then black with oxidation).