I thought they were golden plates?
I think the seers stone was to interpret the plates with - but I might be wrong. Prior to making up the Mormon religion, Smith used the seer stone(s) to dowse for water and look for lost treasure iirc. Put the stone in a hat, look into the hat, and then recite the passage that was “revealed” to him while someone transcribed.
I think their were two stones, called the Ummim and the Thurmim. Such devices are also mentioned in the Bible, and were used by the High Priest iirc.
Yes, there were golden plates, but they weren’t written in English, so Smith said he had to “translate” them, with heavenly assistance, by looking at a stone he dropped in a hat.