Vivianite – The Necro-Crystal
I have been looking at this crystal since we just got in for a few days ago and I can’t put it down. In fact, I’m fascinated so much that I’ve already taken a few breaks while writing this to play with it. (That’s what she said).
You see, this crystal is a brilliant emerald green when you pick it up, but the second you tilt it the crystal you discover a vibrant royal blue color that whisps through the specimen. Imagine a bright blue fire igniting inside the crystal. It’s fascinating.
This phenomenon is called Pleochroism. This is when a crystal or mineral displays two different colors depending on which direction you are looking at it. The most common pleochroic crystal you might recognize is Tanzanite. Tanzanite can change from blue to purple depending on the direction you are holding it.
As a gemologist I’ve handed hundreds of Tanzanite gemstones and I can confidently say that they don’t hold a candle to quality of the same phenomenon displayed in Vivianite, however, the crystal changing colors is surprisingly not what prompted me to write about it.
Crystals Growing on Dead Bodies
I stumbled across an article about Vivianite that prompted a lot more research into this mineral. I found that Vivianite is found on sea shells, other minerals, and cast iron artifacts and even more surprised when I discovered that Vivianite has also been found on decomposed human remains. You read that right, Vivianite is found on dead people.
To understand how this could happen, we have to look at the chemical composition of Vivianite - Fe2+Fe2+2(PO4)2·8H2O or, for the those of us that are not chemistry nerds - Iron, Water and Phosphate.
Iron is wildly abundant in the ground and is the mineral that gives most dirt its red color.
Phosphate is a salt that is common in the earth but is also in our bones and is released once our bodies start to decompose.
Once the Phosphate is secreted and comes into contact with iron and Water in the ground, clear Vivianite crystals grow. The crystals get their blue and green colors after they are exposed to oxygen.
Imagine being an archeologist who just discovered an ancient colony buried underground. Excited, you uncover as many remains as you can for your research only to find blue and green crystals growing on all the bones you uncover. As fascinating and strange as it sounds, it can quickly put a stop to any DNA research you can do on the discovery. The only thing you will really know is that the body was decaying in a water and iron rich soil.
Vivianite was discovered in England in 1817. Vivianite is a very fragile mineral and can be easily scratched ranking it a 2 on the Mohs Hardness Scale. It has a monoclinic crystal structure meaning it forms in thin sheets that are held together by very weak bonds. For reference, this would give it the same crystal growth pattern of clear Selenite.
Vivianite Meets Oxygen
Vivianite gets it’s color from oxidation inside the mineral ,not the outside. The light photon knocks an oxygen proton off the water molecule causing it to balance the charges.
Basically, light reacts with the mineral and changes the water molecules causing it to gain its blue/green color initially very quickly. Over time that blue/green color can change to dark indigo and even to black. With even more exposure, Vivianite mineral will morph into Metavivianite.
If you have Vivianite in your collection, be mindful of the amount of light it receives. Don’t worry, this process of morphing takes a lot of time. Enjoy your specimen and some great conversation points about this strange mineral.