As of 12-28-2013, there are two full collections and -only- the items in the two collections which spawn in 'The Aethenaeum of Shadows' in 'The Obelisk of Lost Souls' ... the West and North rooms each have one ground spawn '?' ...
- Enchanted bone fragments collection - Glowing shards collection
68 warden, on the Draconic language quest ... went AFK (everything in the zone is gray) came back a minute later to see that both of the '?' in the Aethenaeum were back - they are on maybe a 1 minute spawn timer ...
Decided to stay just to see what would come up and within 20 minutes I had all but 3 collectibles from both sets, took another 10 minutes to get 2 of those ... the final 'enchanted gnoll fragment' I gave up on after another 10 mintues, what with the law of diminishing returns working against me ...
Ended up with stacks of 2 and 3 for most of the items in both collections ...
-rincewind
Also, up in the 'Keeper of Nihility' room above - where the Keeper has to be cleared to get down to the Anthenaeum - both sets of collectibles spawn also, but there is only 1 ground spawn node up at a time there