This pallid crystalline remnant ripped from the body of a Voidwalker bears no resemblance to any stone documented in recorded history, except Translucent rocks, Ice ores, Sparkling stones, Snow geodes, Shivites, and Froststones.
Used to obtain additional key items used as a substitute for voidstones in the final voidwatch chapter. This item functions much like voiddust, only at a ratio of 4 of these to 1 entry item. Trade to the glowing spot of the ground inside the Walk of Echos
Some of you might be finding Crystal Petrifacts on your adventures. As stated in the version update notes, this item will be required for the final chapter of Voidwatch, but currently cannot be used.
This item will be the equivalent of Voiddust once the final chapter is implemented. By exchanging a certain amount of Cystal Petrifact, you will be able to obtain trigger items to challenge the monsters of the final chapter.
That said, while it may just be taking up space in your inventory right now, you might want to hold on to them for future use. Unlike Voiddust, Crystal Petrifact can only be obtained under certain circumstances and is not designed to be sellable.