A unique mineral with a vibrant green color is considered a necro-crystal due to its ability to form on decomposed bodies.
What Is Vivianite?
Vivianite is a mineral that grows on organic matter like animal waste deposits, fossil shells, and cast iron artifacts. It was discovered in Cornwall, England, in 1817 by English mineralogist John Henry Vivian. This crystal is famous for its ability to grow on dead human bodies, earning its name as the 'crystal of death.'
This crystal shows a brilliant emerald green color when picked up. However, it displays a vibrant royal blue color the moment it gets tilted. This phenomenon is known as dichroism, or the ability of a crystal to display two different colors depending on which direction it is observed.
When freshly formed, the crystal is usually pale white or transparent and its color actually changes when exposed to light. This is due to oxidation, which makes the mineral darken through shades of blue, to darker green and purple, and then purplish black.
The color of vivianite is due to oxidation that takes place inside the mineral, not the outside. It initially gains its blue/green color as the light reacts with the mineral and changes the water molecules. As light photons knock an oxygen proton off the water molecules, the charges get balanced.
Vivianite develops in iron-rich sedimentary deposits which contain decayed wood, bones, and other organic materials, particularly clay and sandstone. They can also be found in hydrothermal replacement deposits and in phosphate-rich granite pegmatites, or the igneous rocks characterized by a coarse texture and interlocking crystals.
This necro-crystal is very fragile and can be scratched easily, placing it in rank two on the Mohs Hardness Scale. This property is due to its monoclinic crystal structure, which means that it forms in thin sheets held together by very weak bonds.
Why Does Vivianite Form on Corpses?
The ability of vivianite to grow on dead bodies is attributed to its chemical composition. Its chemical formula is Fe2+Fe2+2(PO4)2·8H2O, which means that it is mainly composed of iron, water, and phosphate.
Iron is a metallic element that is abundant in the ground and gives most dirt its red color. Meanwhile, phosphate is a salt commonly found on our planet and in our bones, especially in our teeth and bones. It is released once our bodies begin to decompose. In rare conditions, the phosphate can react with water and iron in the surroundings to form mineral vivianite.
Vivianite has been observed on the bones and teeth of human bodies which have been buried for several centuries. There are also cases where it was found on the tusks of mammoths and the bones of other animals from thousands of years ago. In a few instances, vivianite is identified on more recent dead human bodies.
In the 1960s, experts discovered human bodies in Lake Walchen, Germany which were partially skeletonized. One of them had formed vivianite between the wax from body fat and the iron plate fastened to it.
In 1998, another group of researchers discovered vivianite on the remains of a US Serviceman who had been reported as missing from Vietnam after his B-26B aircraft went missing. Analysis of the minerals that formed on the body led the experts to conclude that the man was likely buried in wet soil alongside parts of the plane, which enabled vivianite to grow.
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