Would help to know what is still silver.
ACHIEVEMENT: you'll have to do at least part of the Challenges to complete the Achievement. Click on the Cup in your Museum to see how many you need.
TREASURE: The treasure pieces don't count as tiles so your locations can be complete despite missing one. Click on the treasure statue & then on the grayed-out icon to find what mine to find it in.
QUEST: Click on the Quest tab to verify if you missed speaking to someone. Also, there was a quest to VISIT the Challenge mines...