Iron Pyrites
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold due to its resemblance to gold. Pyrite is the most common of the sulfide minerals. The name pyrite is derived from the Greek, “of fire” or "in fire”, from. This name is likely due to the sparks that result when pyrite is struck against steel or flint. This property made pyrite popular for use in early firearms such as the wheellock.

Nordic Gold
So-called "Nordic Gold" is a modern alloy used for the middle euro coin denominations, and a term ripe for exploitation by crooks and scammers.

Almost Anything on eBay Described as "Gold"
It's perhaps rather sweeping of us to say this, but we see so many things, including coins, offered for sale, particularly on peer-to-peer auction sites such as eBay, which are not gold. If in doubt, avoid!
See our various pages about eBay.