Vivianite
Vivianite is a hydrous iron-phosphate mineral that grows in long, prismatic crystals. In its pure form, Vivianite is colorless and transparent, it develops in color as it oxidizes, which happens almost immediately. It oxidizes from light green to dark green, to black. It is a brittle mineral, only a 1.5 - 2 on the Moh's Scale, similar to Talc. It is very breakable, due not only to the softness of the mineral but the sheet-like cleavage of the crystal. Its brittle composition makes it a poor choice for jewelry, it's really more of a display piece, which is a shame considering its beauty.
Vivianite is a spooky mineral, it grows in detritus. It replaces organic matter like bones and teeth in peat bogs. It is often found growing in fossilized shells and bones. It grows in phosphorous rich environments.
Vivianite stimulates the Heart Chakra, promoting compassion both toward others and yourself. It grows from dead stuff, taking the old and icky and turning it into something incredible. It does the same with energy, it recycles old stale energy and heals old emotional wounds, creating space for newer and better experiences. Vivianite can reignite an emotional flame, reanimating passion and optimism.