Sylvan stone

Sylvan stone was a crystal that formed on the Prime Material plane at locations where it intersected with the Feywild.

Description
They felt particularly warm, as if they were set out in the wilderness of the Feywild to absorb the rays of setting sunshine.

Usages
Alchemists knew how to extract rainbow-colred glinting essence of sylvan stones for the use in potion-making. When such essence was combined with certain types of alchemical suspensions, they formed oil of diminution.

Notable Locations
Some sylvan stones formed in the caves beneath the Putrig Bog within the lair of the green hag known as Auntie Ethel.