an engraved stone key

This key is made of grey stone. Some runes can be seen on it, but they don't seem to have any meaning. It is pretty heavy.

It is an engraved stone key.
It weighs three pounds.

You identify an engraved stone key.
It is an unsellable key.
It weighs two pounds and ten ounces, and it is worth about five celeb.
Its keywords are key, stone, and engraved.