Glowing Stone is a glowing green or yellow material that is often seen embedded in Brickwork altars and pedestals. It is often first seen in the brickwork pedestals where Potions and Wands spawn in the Mines, but is present in most areas in the game in one form or another.
There are several variants of Glowing Stone in the game, mainly differing in colour. They all behave in very similar ways.
Glowing Stone is just as strong as the brickwork which usually surrounds it, although in many cases when an item has been retrieved from the pedestal it's contained in, or a perk has been picked from the perk altar, the Glowing Stone is converted into Blood (or, in certain cases for the Perk Altar, Water).
It is otherwise fairly unremarkable, apart from its bright glowing colour which is sometimes used to display glyphs with hidden messages.