Specimen at a glance
| Mineral | Vivianite |
|---|---|
| Chemistry | Fe3(PO4)2·8H2O |
| Mohs hardness | 1.5–2 |
| Crystal system | Monoclinic |
| Form | Raw / rough |
| You receive | The exact specimen pictured |
About this specimen
A single bladed vivianite crystal — the mineral that does something almost nothing else on a shelf will do. In ordinary room light it reads as a dark, near-black splinter with a faint green-blue cast. Put a light behind it and the whole blade lights up in saturated emerald-to-teal green, as the first photograph shows. That is not a coating or a treatment; it is the crystal’s own strong pleochroism, its colour changing with the direction light takes through it.
Vivianite is a hydrated iron phosphate, and its colour is chemistry in slow motion. Freshly mined crystals are often colourless or pale and darken through blue and green toward near-black as the iron inside them oxidises on exposure to light and air. A dark vivianite is a vivianite that has been out of the ground a while.
The blade here is a classic habit — flattened, striated along its length, splintery, and splayed into a fanned, frayed split at one end where the crystal separated along its perfect cleavage.
Handle this one gently. Vivianite is Mohs 1.5 to 2, softer than a fingernail, with one direction of perfect, almost micaceous cleavage, so it flexes and peels rather than breaking cleanly. Keep it out of direct sunlight to slow further darkening, do not wash it, and store it where it cannot be pressed against other specimens.
Vivianite: the science
- Vivianite is light-sensitive. Exposure to light speeds oxidation and darkens the crystals over time.
- It is soft enough to scratch with a fingernail and has one perfect cleavage, so thin blades bend and split easily.
- Vivianite has been found growing on buried bones, fossils, and even in old shipwrecks and graves, wherever iron and phosphate meet.
Go deeper
Want the full story on vivianite: how it forms, how to identify it, and what makes a great specimen?
Questions about this piece
What is vivianite?
Vivianite is a hydrated iron phosphate. Fresh crystals can be nearly colorless or pale green, and they darken to deep blue-green as iron in the structure oxidizes.
How hard is it, and how should I care for it?
It rates 1.5–2 on the Mohs scale. Very soft and light-sensitive. Store in the dark, in a closed box, and handle as little as possible. Do not wash.
Is this the exact piece I will receive?
Yes. This listing was photographed individually, and you receive the exact piece shown in the photos.
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