Looking through the wiki, and the general consensus from many H&H'ers out there, bone clay is useless. I feel, not entirely, as Akai Gake is gaga for porcelain plates right now, the buffs to our table worth the effort. However, I'd like to see more uses for Bone Clay (and for JnL to get Cave Clay to be higher than q10).
How about something like a Porcelain Tea Set under the glasses section of the Symbel? It could take four pieces of bone clay, and at q10 give -2% base hunger and +2% FEP event bonus. A "Fine China" variant could require a gold nugget and a silver nugget and give -7% hunger and +4% FEP @ q10.
Another idea could be a curio, the Collectible Plate, made with 3 bone clay, giving 2000 LP, with a MW of 7, a study time of 30 hours, takes up a 2x2 space, and has Jorb's lovely visage on it.
Now, as for the ingredients, I can't believe the materials for bone clay don't have more recipes. Not to mention, Rattle-Tattle Talisman?! Seriously? Feldspar should be embarrassed to associated with this. It needs to be buffed or something. I seriously doubt someone could sell a q9001 Rattle Tattle Talisman right now if their life depended on it.
Alright, if anyone has other ideas on improving bone clay, cave clay, feldspar, and/or bone ash, post them here. I'll add more when I devise some.