TENGCHONG, CHINA—On an overcast spring morning, a mosaic of life in the heyday of the dinosaurs takes shape piece by piece in this border city. It sprawls across hundreds of tables, on sheets spread by storefronts, and under glass counters in shops. Some vendors hawk jade or snacks, but most everyone is here for the amber: raw amber coated in gray volcanic ash; polished amber carved into smiling Buddhas; egg-size dollops of amber the color of honey, molasses, or garnet. Some browsers seek treasure for their own collections, whereas others act as virtual dealers, holding amber pieces in front of their smartphones and snapping images for distant buyers.
