Acquired 9 Obsidian in a 24 hr. period. Two dropped between floor 500 and 600, and seven were from Eternal item conversion. Two of the Eternal conversions were consecutive.
I also had a “loot imp” drop me two Eternal items and a Crystal item all at once, also between floor 500-600.
This is especially exciting because usually it seems I go through hundreds of Legendary items before landing an Eternal. Sometimes I check my gear to make sure I have my Eternalized Lance in play.