"A mirror reassembled from several pieces."
Alina's Mirror (actually called Alina's broken mirror in the dialogue) is a quest item which takes quite a bit of work to get. Geralt must first find all the shards of the mirror, which are scattered about the fields outside the village of Murky Waters. Then he must have them reassembled by either the blacksmith, or the Elven craftsman. In either case, it costs 100 
to have this done.
Once reassembled, the mirror is used to try to help Alina's spirit pass on.