On a mission to find vintage bottles, we dug deep—10 feet deep—to uncover cobalt glass bottles, including Bromo bottles and some unique finds like Dr. Thatcher’s worm medicine and the rare ...

Cobalt glass is more rarely used than clear glass and other colors of glass. The Ardagh Glass plant in Port Allegany, for instance, makes cobalt glass containers only every other year.

Some common forms of cobalt include cobalt-60 and cobalt chloride. Cobalt blue is a vivid color used in artwork. ... One 2014 study found cobalt blue glass beads in a Danish grave 3,400 years old.