This is a really beautiful example of the rare mineral Vivianite, with the most beautiful green blades in matrix, this particular piece was sourced from Amazonas Brazil. 
Vivianite is a soft mineral, with Mohs hardness only 1+1⁄2 to 2, and specific gravity 2.7.
Metaphysical properties 
It is said that Vivianite assists mental clarity and helps one to dive deep into their heart, healing any old wounds, opening and balancing the heart chakra.
A fab little fact about Vivianite is that it is notorious for darkening upon exposure to light, so is clear when mined, then turns blue/green.