This state symbol really rocks!
- Meghan McMahon
- 4 days ago
- 3 min read
There are so many things that represent the state of Illinois — plants, animals, and … minerals? Yes, some of the state symbols can even be found beneath the surface. There is one that can be found in one form or another in many places: fluorite.
Before we talk about fluorite, let’s talk about what a mineral is. A mineral is a solid substance that is found deep below and even on the Earth’s surface, such as in rocks or sand. Minerals are inorganic, which means they are not made by a plant or animal.
Words to know
Document: To record in written, photographic or other form.
Impurity: Something that impairs the purity of a substance.
Transparent: Allowing light to pass through so objects behind it can be seen.
There are thousands of different minerals in the world, and you might be more familiar with them than you think! In fact, you might have eaten one today. Halite is a mineral that we more commonly call rock salt. Other common minerals include calcium, gold, silver, sulfur, copper and pyrite (also known as fool’s gold).
How do you know which mineral is which? Scientists test and document different qualities of minerals, some of which include the following:
Color: What color is it? Some minerals come in many colors.
Streak: Scrape the mineral across a surface. What color does it leave behind? Sometimes it is a different color than what it looks like with the naked eye!
Hardness: If you drop it, will it chip? What if you slam it down? Mineralogists, scientists who study minerals, use the Mohs scale to determine hardness. Minerals are assigned a number, with 1 being the softest and 10 being the hardest. The softest mineral is talc (which you might have heard of in talcum powder), and the hardest is a diamond. That’s why so much jewelry contains diamonds; they are sure to last!
Luster: How does it reflect light? Is it shiny? Dull?
Cleavage: How does it break? Some minerals break into cubes, others thin sheets.
What other questions might you ask about a mineral?
Back to Illinois. In 1965, the state announced its mineral representative: fluorite. In the early 20th century, Illinois was one of the leading producers and miners of fluorite. Here are five facts about this important mineral:
You might have used parts of this mineral today! Fluorite is made of the elements calcium (Ca) and fluorine (F). Fluorine can turn into fluoride that is found in toothpaste!
Pure fluorite is colorless and transparent. However, there are often impurities (teeny, tiny flecks of other elements) that make it colorful. It is found in shades of dark purple, amethyst, light blue, light green, yellow and clear. It is sometimes referred to as the most colorful mineral in the world!
It can be found in South Africa, China, Mexico, Mongolia, the United Kingdom, the United States, Canada, Tanzania, Rwanda and Argentina. Large deposits are found in southern Illinois. People throughout history have been using fluorite for all sorts of objects, including jewelry, trinkets, sculptures and even vases and cups.
The word “fluorite” means “to flow” in the Latin language. Fluorite melts easily, so it is used in making other things, such as aluminum, iron, glass, plastics and cement. If you’re wondering if it is lower on the Mohs scale because it melts easily, you’d be right. Fluorite ranks at the softer end of the scale at 4.
Fluorite fluorescing under ultraviolet light. (Photo via Shutterstock) Fluorite can fluoresce under UV light. This means it can glow under the same blacklight used for things like glow bowling. You might have noticed that the action is named after fluorite. The light emitted from fluorite depends on the original color of the mineral and where the mineral was found. Different impurities found in different places mean different colors. Under UV light, fluorite can emit blue, red, purple, yellow, green and white light. Wow!