A slogan is a short statement that makes it easy to remember the good qualities of something, so a slogan that focuses on the element cobalt will extol its many virtues. For example, mix the two definitions of Cobalt, by referencing color and nutrients, good health. The element's blue color is an easy point of focus for memorization and discussion of cobalt's unique features.
Slogans for elements like cobalt can be seen as being similar to poetry about the element. For example, this haiku about cobalt discusses its use and its unique pigment: "Shiny surfaces/ Porcelain, glass, pottery, tile/ Beautiful dark blue." This haiku references the fact that cobalt is used as a pigment in creating different artistic products, but this isn't the only thing that cobalt is known for. Cobalt is also used in the manufacture of metal alloys that are used in the aviation manufacturing sector thanks to its resistance to corrosion. Magnets made with cobalt are used for everything from manufacturing electric guitar parts to motors used in high-speed vehicles. In its radioactive form, cobalt is used in the treatment of cancer, adding yet another dimension of use to this versatile element.