The 50th annual GeoFair is Cincinnati’s largest gem, mineral, fossil and jewelry show. This year’s theme is “American Mineral and Fossil Treasures,” with displays containing private, university and museum-quality specimens, along with vendors and wholesalers, a swap area and free fossil, meteorite, mineral and gemstone identification. Demonstrations include gold panning, geode cracking and gemstone polishing. Children younger than 12 will receive free mineral and fossil specimens upon entry. 10 a.m.-6 p.m. Saturday; 11 a.m.-5 p.m. Sunday. $9 adults; $3 kids; free for uniformed scouts. Sharonville Convention Center, 11355 Chester Road, Sharonville, geofair.com.