Sand, soda, and lime

“Certain materials and industries were ready made for this color explosion. Since ancient times, the vitreous arts―enameling, pottery, and glassmaking―had provided consumers with a modicum of color in an otherwise drab man-made world. Pottery and glass could readily be colorized by adding small amounts of metallic oxides, such as cobalt, copper, or manganese, to the glaze.”

From Progress to Modernity: Invention and Innovation at the World’s Fair by Regina Lee Blaszczyk