Today’s Wonder of the Day was inspired by Sequia. Sequia Wonders, “What is fool's gold?” Thanks for WONDERing with us, Sequia!

Have you ever heard the phrase “all that glitters isn't gold"? It means that just because something is shiny and golden, it's not necessarily gold…or valuable. As it turns out, it's absolutely true, too!

Gold is a chemical element. It's a soft, shiny, bright yellow metal that happens to be very rare. It doesn't react with many other elements, so it's often found in its pure elemental form of nuggets or grains in rocks found in stream beds or veins in larger rock formations.

Because of its natural beauty, rarity, and many practical uses in jewelry and industrial applications, gold is one of the most valuable precious metals in the world. As a result, gold has been sought by people for thousands of years.

The discovery of gold has at times sparked a frenzy. For example, when gold was discovered in the American West, a “gold rush" occurred, which brought thousands of people west to mine for gold in the hope of getting rich quickly.

As these new miners searched western stream beds for gold, some found gold and made money. Many others found something that glittered but wasn't gold.

Pyrite is a shiny mineral made of iron and sulfur that looks very much like real gold. It's not a metal, however. It's an iron sulfide with the chemical formula FeS2.

Pyrite gets its name from the Greek word puritēs, which means “of fire" or “in fire." This is because pyrite can create a spark when struck against steel. In fact, pyrite was popular in the 16th and 17th centuries as a source of ignition in the earliest firearms.

Pyrite is much harder and more brittle than gold. Unlike gold, it also tarnishes to a dark brown when exposed to oxygen.

Pyrite is very common and its resemblance to real gold has fooled many. This led to its nickname: fool's gold. Unlike real gold, though, pyrite does not have great value.

Simple field tests and close observation can be used to distinguish between real gold and fool's gold. For example, real gold usually takes the form of a nugget or very small flakes or sheets. Pyrite, on the other hand, forms crystals shaped like cubes, octahedrons (8 sides), or pyritohedrons (12 sides).

Gold and pyrite also have different physical characteristics. Gold is softer and can be cut. Pyrite is very hard and cannot be scratched. Gold has no odor, whereas pyrite often smells like sulfur or rotten eggs. If you strike gold with a hammer, it will flatten or change shape without breaking. Pyrite will give off sparks when struck with a hammer.

Today, pyrite is sometimes used to make sulfuric acid for industrial purposes. Since it's an attractive substance, it is also sometimes polished and used as an inexpensive gemstone in jewelry.

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We hope tomorrow’s Wonder of the Day will be an UDDER delight!