Yes, rocks are often made up of different kinds of minerals. In fact, most rocks are composed of two or more minerals, although some rocks can be composed of just one mineral.

Here's why:

* Minerals are the building blocks of rocks: Just like a house is made of bricks, wood, and other materials, rocks are made of minerals. Each mineral has a specific chemical composition and crystal structure.

* Variety in mineral composition: Different rocks form under different conditions, leading to different combinations of minerals within them. For example, granite contains quartz, feldspar, and mica, while limestone is primarily made of calcium carbonate.

* Identifying rocks based on minerals: Geologists use the minerals present in a rock to classify and identify it.

However, it's important to note that:

* Some rocks are monomineralic: These are rocks composed of only one mineral, like quartzite (made of quartz) or halite (made of salt).

* Rocks can also contain other materials: Besides minerals, rocks can contain organic matter, volcanic glass, or even fossilized remains.

So, while many rocks are made up of different kinds of minerals, there are exceptions to this rule.