Rocks and minerals

What is a mineral?

A mineral is made of the same substance all the way through. There are about 5000 known minerals on Earth and many are essential for improving the way we live our lives. Almost any piece of technology, including what you're viewing this on now, uses specific minerals to function! Some minerals, like tiny amounts of copper and iron, are even required for human life.  

What is a rock?

A rock is made up of two or more minerals. Our homes, schools, places of work and roads are all made of rocks, we have learned a lot about which rocks are best for certain buildings and activities given their unique properties! Have you ever broken a piece of chalk? Then you know while it may be ideal for drawing, it would not make a strong building. 

There are three types of rocks. The Rock Cycle can be used to explain how rocks change from one type to another.

Rocks vs. Minerals

The Rock Cycle can be used to explain how rocks change from one type to another. Image: Santa Fe College 

1. Igneous

• Forms from liquid rock (lava and magma) 
• Think of freezing water - as it cools crystals form
• Other rocks can be turned into igneous rocks if they are heated so much that they melt
• E.g., Granite

2. Metamorphic

• Forms when an existing rock is re-heated (without fully melting). Involves a lot of heat and pressure
• Think of a tadpole turning into a frog. It becomes something else on the outside while staying the same on the inside
• E.g., Gneiss

3. Sedimentary

• Forms from pieces of pre-existing rocks that undergo weathering and erosion followed by cementation 
• Weathering is the process of breaking down an existing rock, and erosion is the process of moving the pieces of rock from one place to another
• E.g., Petrified Wood, Ripple Marked Sandstone, Glacial Striae

Click on a Mineral name to learn more about it!

Fluorite

Fluorite is really interesting! When you find it in a rock, all the little crystals will usually be in the shape of cubes. This is the way that the mineral naturally grows!  

Fluorite is a soft rock which can be scratched with a common nail (ask your parents for help with this). Some people even like to carve it into sculptures. Fluorite can be found in many different colours.

 Fluorite image source. 

 

But the coolest thing about fluorite is that it is fluorescent! What does this mean? It means that if you have an ultraviolet light/ a black light (the lights that they use in glow in the dark mini-putt that look purple) and you shine it on the rock then it will glow!!! Fluorite from two different places might glow two different colours under the same light. 

Fluorite. University of Waterloo Earth Sciences Museum Collection

Used in: 

• 
  Toothpaste: Fluoride is one of the main elements in fluorite. It helps prevent and sometimes reverse the early stages of tooth decay
• Drinking water: Fluoride is also found in drinking water! Don’t worry, it’s good for your teeth and won’t hurt you in small doses

Fluorite. University of Waterloo Earth Sciences Museum Collection

Copper

Have you ever had a ring that turned your finger green? If so, it was probably made out of copper! 

Copper is a natural metal. It absorbs heat very easily which is why we sometimes use it to make pots and pans for cooking. We use it in electrical wires too because electricity flows through it really easily.  

Copper. University of Waterloo Earth Sciences Museum Collection

Copper is one of only two coloured metals (the other is gold). It is usually a reddish brown colour but it turns green when it’s exposed to air for a really long time (think of the green colour as a form of rust). 

Used in:

• 
  Pennies
• Electrical wires
• Water Pipes
• The Statue of Liberty is made of copper, and all the parliament roofs in Ottawa (the green roofs) are made of copper too.

It's strange to think about, but we eat copper sometimes! A little bit of it is actually good for us. It is found in hot chocolate powder, chocolate, sesame seeds, nuts, calamari, lobster and many other foods! 

Penny Experiment

If I ask you what a penny is made of, you would probably say copper. This is correct, but it’s not the only thing that pennies are made of! Try this:

1. Collect a lot of pennies from different years, and a strong magnet
2. Line up the pennies in a line according to the year they have on them
3. You will probably notice that the really old pennies don’t stick to the magnet. This is because the price of copper used to be a lot lower so we used to make our pennies entirely out of copper. Copper isn’t magnetic
4. You will also notice that the recently made pennies also don’t stick to the magnet.  Because copper is now quite expensive, we’ve started to make our pennies out of zinc with a copper coating. They will feel a lot lighter than the pure copper pennies because zinc weighs less than copper. Zinc is also not magnetic
5. But all the other pennies should stick to the magnet! We used to make pennies out of steel with a copper coating. And steel is magnetic! 

Pretty cool eh?

Copper Ingot. University of Waterloo Earth Sciences Museum Collection

Pyrite

Pyrite is also known as “Fool’s Gold”. It is a very pretty mineral and usually forms interesting crystals. 

The word “Pyrite” comes from the Greek words pyrites lithos, meaning “stone which strikes fire”. They discovered that when you hit pyrite with iron it would spark. This is why it was used to start fires!

Pyrite was also polished by Native Americans in early times and used as a mirror!

At the University of Waterloo’s Earth Science Museum we have a display dedicated to the different crystals of pyrite. 

Used in: 

• Jewelry (Called Marcasite)
• Pyrite sparks when you hit it with steel, so it was used in early rifles
• Used in the manufacturing of paper and ink

Gypsum

Gypsum forms deep under water when creatures like clams, oysters, scallops and other shellfish die. Their remains settle to the ocean floor in layers. Over time, hundreds of layers form and push down from on top of the original layer. This causes it to be turned into rock. Some of this rock contains gypsum.

Gypsum is a very soft mineral. It can be scratched with your finger nail!

Gypsum. University of Waterloo Earth Sciences Museum Collection

Used in: 

• Manufacture of Wallboard
• Cement
• Plaster
• Fertilizer
• Used to make medical casts (they put this on you when you break a bone!)

Gypsum "roses". University of Waterloo Earth Sciences Museum Collection

Quartz

Quartz is one of the most abundant minerals on the planet. It comes in a lot of different colours such as pink (rose quartz), yellow (citrine), purple (amethyst), white (milky quartz), red (amethyst with hematite), and brown and grey (smoky quartz). When we want quartz today we often make it in a furnace instead of digging it out of the ground.

Quartz is used in watches! A battery powers a microchip, which sends messages to a quartz crystal, causing it to vibrate 32,768 times a second. Every time the quartz vibrates that exact number, it sends a message to a motor which turns the hands on your watch!

Quartz has been found on the moon!

Quartz Crystals. University of Waterloo Earth Sciences Museum Collection

Used in:

• Watches
• Gemstones
• A source of silica for glass
• Electrical components
• Optical lenses
• Sandpaper 

Calcite

Calcite is a very common mineral found in most places on earth. Calcite comes in over 300 different shapes, this is more than any other mineral. Pure calcite is colourless or white, but due to impurities it may also be red, yellow, green, honey, pink, lavender, black, brown or blue.

An interesting way of identifying calcite is the acid test. When you place a drop of weak acid, such as vinegar, on calcite it will bubble!

Calcite. University of Waterloo Earth Sciences Museum Collection.

Used in: 

• Concrete and asphalt 
• Making medicines, such as antacid tablets (chewable tums)
• Fed to chickens
• Buildings

Calcite. Variety Dog Tooth Spar. University of Waterloo Earth Sciences Museum Collection

Sodalite

Sodalite is a vibrantly blue mineral which was named for its high sodium content (sodium is in table salt!) It has a greasy lustre, which means that if you can get a good look at a clean crystal then it will look like the surface of the mineral is greasy.

Sodalite is a highly fluorescent mineral. This means that if you have an ultraviolet light (a black light/ the light that is used for glow-in-the-dark mini putt) and you shine the light on a piece of sodalite then it will glow!

Sodalite. University of Waterloo Earth Sciences Museum Collection

Use​d in:

• Decorative pieces
• Jewellery

Sodalite. University of Waterloo Rock Garden

Mica

Different forms of mica have different names. For example, white mica is muscovite, while black mica is biotite. No matter what the colour, the properties of this mineral group are similar. It is very flexible, you can bend it in one direction and when you let go it will return to its original shape. It is also very soft and you can scratch the surface of mica with your fingernail. Crystals form with really strong bonds in one direction, and really weak bonds in another direction. Because of this, the crystal can be broken apart in sheets!

Used in:

• toasters
• Sparkles in cosmetics
• Old stove windows
• Makes your camera flash

Biotite Mica (left) and Muscovite Mica (right). University of Waterloo Earth Sciences Museum Collection.

Phlogopite Mica (left) and Lepidolite Mica (right). University of Waterloo Earth Sciences Museum Collection

Labradorite

Labradorite was first discovered in 1770. It was named after Newfoundland and Labrador in Canada, but it is also found in other areas of the world. Labradorite is a type of feldspar (the most abundant mineral family) with stunning colours and visual effects. Its colours can range between violet, blue, green, yellow and even orange-red. These colours are only viewed when rotated at an angle and appears through the entire surface of the stone.

 Labradorite. University of Waterloo Earth Sciences Museum Collection

Used in: 

• Decorative pieces
• jewelry

Labradorite. University of Waterloo Rock Garden

Magnetite

Magnetite is a magnetic rock. In fact, it is the most magnetic mineral on earth. Naturally magnetized pieces of magnetite are called lodestone. It is black and shiny.          

There's a piece of magnetite in the Peter Russell Rock Garden. Bring a magnet with you the next time you visit and try to figure out which rock it is! Magnetite image source

Used in:

• Early compasses 
• An ore or iron
• Pigment in paints
• In fertillizers

Want to find your own magnetite? It’s simple! All you need to do is run a magnet through sand. You should find that little tiny grains of black sand sticks to the magnet, while all other sand doesn’t. What you’re collecting is tiny grains of magnetite! Don’t forget to put it into a plastic bag so that you don’t lose it!

Magnetite fillings image source.