ology logo

Start a
Rock Collection

Every rock has a story to tell. Rocks hold evidence that helps us figure out how mountains formed, where glaciers once flowed over the United States, or what kinds of plants and animals lived on Earth. Rocks show us how Earth has changed and how it's still changing, even today! They give us important clues about Earth's history.

two boys displaying their rock collections

You can begin learning about rocks just by looking at them. If you look closely, you'll notice that rocks from different places have different textures, shapes, and colors. These observations give important clues about what a rock is made of and its history. For example, a rock might become smooth and round after years of grinding against other rocks in a river or near the coast of an ocean. A jagged rock has probably been through less wear and tear from wind, rain, or ice.

You can find rocks almost anywhere. Here's how you can start your own rock collection.

Step #1: 
Collect Your Rocks

2 boys outside with a bucket looking for rocks

The first step to making a rock collection is finding your rocks. You'll find rocks just about anywhere. If you want a good variety of rocks, be sure to look in many different places. Rocks can be very different depending on where they come from!

It's also important to record information about each rock you find. This information helps tell the story of each rock.

There are just a couple things to remember:
1. Don't go alone.
2. Make sure you always have an adult with you.

Materials

picture of the materials needed including buck, zip lock bags, a permanent marker, and rocks
  • Sandwich bags
  • Small shovel or spade
  • Permanent marker
  • Printout of My Rock Chart
  • Bucket, bag, or backpack to carry your rocks
  • Deep bowl, pot, or bucket to clean your rocks
  • Soap or dishwashing liquid to clean your rocks
  • Old rag or paper towels

What To Do

1

Look for at least 10 rocks in different places, like a playground, park, beach, or along a lake or river. Avoid collecting from places like gravel pits or gravel dunes. Choose rocks that are easy to carry, but not too small. Try to select rocks that are at least as big as your fist.

2

If part of a rock is buried, use your shovel to dig it out.

3

Put each rock in a separate sandwich bag. Use your marker to write the rock number (starting with 1) and the date on the bag.

dropping the rock into the ziplock back
labeling the bag with permanent marker
4

Write the rock number and date on your Rock Chart. In the next column, write the place where you found the rock. For example, was it at a park? Under a tree? By the road? Was it with other rocks? Write down any additional information in the Notes column.

5

Place the rock sample in your bucket, bag, or backpack.

6

When you get home, clean your rocks. Put warm water and soap in a bucket and rinse off each rock, one by one. Wipe the rock with a rag or paper towel to dry it completely. Then place it back in its bag.

washing a rock in a bowl
drying off the washed rock

Step #2:
Observe and Sort Your Rocks

When geologists study a rock, they examine its shape, size, texture, and color. They consider where the rock was found, too. But they also study things they can't see, like a rock's hardness. Geologists use special instruments to test rocks in the lab.

Now it's your turn to examine the rocks you found. After you record your observations, sort them into different categories. You can organize them by physical traits, like shape or color. You can also organize them by where they were found.

Materials

  • Your rock samples in their bags
  • Printout of My Rock Chart
  • Pencil

What To Do

1

Be sure you have your Rock Chart, your rock samples, a pencil, and a big place to work. Spread out your rocks on the table or floor.

washed rocks spread out on towel to dry
2

Now take the rock out of its bag. Look at it closely. Turn it around in your hand. Feel its texture. As you examine the rock, consider the different traits below. As you do, record your observations in your Rock Chart.

  • Size: How big is it? Think of something about the same size, like an apple or a kiwi.
  • Color: What color is it? Is it the same color all over, or is there a mix of colors?
  • Texture: How does it feel? Is it smooth, rough, or bumpy?
  • Shape: What shape is it? Is it flat? Round? Does it have sharp edges? Think of something with a similar shape, like a lemon or a strawberry.
2 boys looking closely at one of the rocks they collected
boy recording observations on the rock chart
3

Now try sorting your rocks into a few different categories. You might organize them by physical characteristics, like color or texture. Or you could organize them by where they were found.

4

Next, choose one way to organize your rocks. Then decide how you would describe each group. For example, if you organized your rocks by size, you might put them into three groups: large (size of an orange or bigger), medium (about the size of a kiwi), and small (the size of a strawberry or smaller). Or if you organized them by where they were found, the groups might be: at the park, near the lake, and in the backyard.

Step #3:
Display Your Rocks

At the Museum, many rocks are on display from all kinds of places. They might be organized by where they were found, what they're made of, or even type of rock.

Now it's your turn to display the rocks you found.

Materials

materials needed including a shoe box, scissors, assorted small containers, a plastic tray
  • Containers to hold rocks. Here are a few ideas. Choose the materials that fit your needs:
    • 1 shoe box or other large box
    • Assortment of small boxes or containers (such as a small store box, a paper clip box, or a film canister)
    • Empty egg carton and scissors
    • Clear plastic tray with small dividers (you can find these at hardware or home stores)
  • Clear plastic wrap (optional)

What To Do

1

In Step #2, you organized your rocks into groups. Arrange the rocks on a table, placing them together in their groups.

2 boys arranging their collected rocks into groups
2

Place each group of rocks into small boxes or containers. You could also put your rocks in the holes of an egg carton. Use scissors to cut out the number of holes you need. Now put your small boxes into a large box like a shoebox.

placing rocks into separate containers
3

If you're using a clear plastic tray or container with dividers, just put your rocks into each section.

placing rocks into container with clear dividers
4

You can make your display labels in different ways. 

  • Cut an index card in half or quarters, then fold and write on the pieces and tuck them into the boxes for 'standing' labels.
  • Or, you can write on one big piece of index card for each of the sections.
cutting an index card
rock display with 3 cards labeled with different categories
5

If you're using a shoebox, cut a large hole in the box cover and cover it with plastic wrap.

shoebox with smaller containers inside that have rocks in them
showing a box top with square cut out and covering with plastic wrap to make a window

Try this!

Can you identify the rocks you found?

Image Credits:

Photos: courtesy of AMNH, Carl Bespolka