Taxonomy term

Iodine is a bluish-black lustrous solid (violet-colored in its gaseous state) found primarily in seaweed, underground brines associated with petroleum deposits and caliche ore deposits. 

Gold was highly valued by early civilizations for its scarcity, durability and characteristic color, reminiscent of the sun, which was worshiped by some as a deity. It was first recovered from streambed gravels (placers), where it occurred in native form, and thus did not require extraction from ores. It was both essentially indestructible and easily worked. Gold nuggets were prized possessions that could be fashioned into bars of different standard weights and into ornaments and items of adornment that also served as portable wealth. Gold leaf (gold beaten into thin sheets) has been used to decorate significant architectural structures since ancient times. In the 7th century B.C., the Etruscans used gold to make false teeth, and it is still used in dentistry today due to its nontoxicity, durability and beauty.

Iron oxide pigments, natural or synthetic, are inorganic materials commonly used as coloring agents. They are valued for their resistance to color-change (especially from exposure to sunlight), chemical resistance, stability under ambient environmental conditions, nontoxicity and relatively low cost.