Cron castle quest

[McGuffin]

ive got a Cron castle quest from Alustin the alchemist.
i am to find alchemical traces there. i found only an altar. the quest doesnt check out.
there is also a quest called "story on cron castle" or something, that i cannot accept from the giant in town, even though my amity is high enough for all of his stuff.

i also cannot abandon or track the quest. what do i do?