Gargoyle dust is used to craft the following items:
If you wish to craft the Kinslayer's Outfit in Dark Mode, make sure to farm all 9 dusts before deactivating the final ward for The Gargoyle Contract.
Nearby gargoyles will no longer respawn once the ward for the area is deactivated. Gargoyle dust is not sold by any merchants and there are no other respawning gargoyles.
is an alchemy ingredient
but is not needed to craft anything. It can be dismantled into powdered monster tissue