Topic – Rocks and Minerals

Rocks and Minerals

What is the difference between rocks and minerals?

A mineral is made of only one substance. It is not a mixture of different substances. A rock is made from a mixture of two or more minerals.

You can think of minerals as different colours of modelling clay. Each colour of clay represents a different mineral. So if you have three balls of clay—one green, one blue, and one red—each ball would be a different mineral. Now imagine that you take a chunk from each ball of clay, press them together, then roll the clay into a ball. This ball would represent a rock because it is made of a combination of minerals.

Granite is a common type of rock. You have probably seen it before. If you look closely at a piece of granite, you will see flecks of different colours. These different colours come from the minerals that make up granite. The minerals in granite are feldspar, quartz, and mica.

Why are some rocks all one colour, unlike granite?

Even rocks that are all one colour contain two or more different minerals. Think back to the ball of modelling clay made from three different colours. You can still see the green, blue, and red clay used to make the ball. But if you mix the clay for a long time, eventually it will all become brownish-grey. The colours mix with each other. In rocks that are all one colour, the minerals have mixed together, so you do not see the different colours.

What do minerals look like?

Minerals do not all look the same. They can be different colours and shapes. Some minerals sparkle and some are dull. Some minerals, such as quartz, form in crystals. Other minerals are metals. Gold and silver are two minerals that are metals. The names of these minerals also tell you what colour they are.

Which is harder—rocks or minerals?

This is a trick question! Some rocks and minerals are hard, and some are soft. Granite is a hard rock that is a great material to use for countertops because it is not easy to scratch or chip. Other rocks, such as sandstone, are much softer. Artists sometimes use sandstone for their sculptures because it is easy to carve. Some minerals are soft enough to scratch with your fingernail. Diamond is a mineral and it is the hardest substance found in nature.

Do I have rocks in my head?

If you do not already, you probably will soon. Rocks are a very interesting subject to learn about, and so are minerals. You may even become a rock collector. If that happens, you may end up with rocks all over the place—in your desk, in your pocket, and in the box where you keep your collection. And you will have many thoughts about rocks in your head.

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