In this activity, students will become familiar with rocks’ physical properties and the basics of rock identification. Students will sort rocks into groups based on their observations and learn about the physical properties of rocks. At the end of the rock ID lab, students can try identifying rocks by type, subtype, and name.

No prior rock ID experience is needed for students to complete this lab activity. Part A especially is a great way for beginners to explore the physical properties of rocks! However, before beginning parts B and C of this activity, students should already be familiar with the rock cycle and the three main types of rocks (igneous, sedimentary, and metamorphic!) and their sub-types.

Before starting the lab, students should also know the difference between rocks and minerals. Often, it makes sense to do a mineral lab before diving into a rocks ID lab. You can find my mineral lab online write up (free) or the printable directions (for purchase).

Please Note: I’ve made the directions for this rock ID lab activity available for free here in this post. However, if you want printable directions, worksheets, flashcards, readings, and teaching posters for a rock ID lab, you can purchase them in my shop. The printable rock ID flashcards are included but also sold individually. Or, you can find all these materials plus more in my complete Rocks and Minerals Unit.

Materials

This activity requires one of each item per lab group unless stated otherwise.

• 10+ rock  samples labeled with numbers 1-10+
  • Recommended: granite, gabbro, rhyolite, basalt, limestone, conglomerate, mudstone, gneiss, slate, and marble
  • You can complete this lab with a different rock sample set, but it is ideal to have a mixture of common igneous, sedimentary, and metamorphic rocks.
• Hand lens or microscope
• Juice of a lemon
• Eye dropper
• Student worksheets (1 set per student)
• Teaching posters
• Rock cards

Modifications (optional)

• To make this rock ID lab simpler, do parts B and C all together as a class.
• As an alternative to parts B and C, you could tell students which rocks are igneous, sedimentary, and metamorphic and then ask students to find some similarities between the rocks within each group.
• To simplify part C, tell your students which 10 rock samples they have, but do not tell them which is which. This allows students to use the process of elimination to identify the most difficult samples.

Directions

Part A: Examine the Rocks

1. Allow the students to familiarize themselves with the rock samples by picking them up, looking at them, etc…
2. Ask the students to take note of which rock samples…
   • Are light colored?
   • Are dark colored?
   • Have several different colors?
   • Are one solid color?
   • Are made of crystals? (use hand-lens or microscope)
   • Are made of sediment particles stuck together? (use hand-lens or microscope)
   • Are fine-grained?
   • Sparkle?
   • Are dull?
   • Are soft or break or crumble easily?
   • Are very solid and don’t break or crumble?
   • Have stripes or layers? (foliation)
   • React to an acid (lemon juice)?
     • Note for acid reactions: rocks with a very high calcium carbonate content (e.g., marble, limestone, and coquina) should react with a drop or two of acidic lemon juice. They will bubble and fizz. Rocks with a lower calcium carbonate content (e.g., some mudstones) may bubble and fizz slightly.

Part B: Rock Types & Sub-Types

1. As a class, review or research the properties of igneous, sedimentary, and metamorphic rocks and their sub-types. Create a list of the properties (texture, composition, foliation, etc…) you might see in each of these rock types and subtypes:
   • Igneous:
     • Extrusive
     • Intrusive
   • Sedimentary:
     • Chemical
     • Clastic
     • Biochemical and organic
   • Metamorphic:
     • Foliated
     • Nonfoliated
2. As you create your lists, introduce/review the following concepts: mafic vs felsic, igneous textures, grain sizes, and foliation. For this step, the teaching posters found in my product will be a helpful visual aid.
3. Students should write detailed descriptions of each rock sample, noting the following physical properties:
   • Texture (use a microscope or hand lens)
   • Composition
   • Luster
   • Color
   • Foliation (use hand lens if needed)
   • Acid reaction (strong reaction, weak reaction, no reaction)
   • Other properties
4. See if your students can correctly identify the type or subtype of any of the rock samples.
   • Start with rocks that can be most easily identified. For example, a rock with clear foliation can quickly be identified as a metamorphic foliated rock. A rock that is made of sediment particles cemented together can be quickly identified as a sedimentary clastic rock.
   • It is OK if there are some rocks that your students are unsure about. Discuss why they are unsure and if there are any types/sub-types they can rule out. It may not be possible to identify certain rocks in a classroom setting.
5. After this part of the lab is complete, reveal which rocks were sedimentary, igneous, and metamorphic. You may also lead a discussion on how the physical properties of rocks relate to how they formed. E.g., large crystals form deep underground, foliation forms under directional pressure, etc…

Part C: Rock ID

1. Pass out the rock information flashcards or a different rock ID guide of your choosing.
   • For an added challenge: encourage students to only look at the front (info/text-only) side of the flashcards while making their IDs. The backs of the flashcards include pictures and names of the rocks.
2. The students should read the properties listed on each flashcard.
3. Students can compare the rock properties on the flashcards to their written descriptions of each sample.
4. Students should do their best to match each rock sample to its correct identity.
5. Rock ID is challenging: assist students if they become stuck.
6. End the lab by revealing the correct identity of each sample.

Study Rocks and Minerals with Wild Earth Lab!

Save time by purchasing all the printable materials you need for a rock ID lab! This set includes all the worksheets, teaching posters, flashcards, and handouts you need for completing this rock ID activity:

OR: you can also find all the above materials plus more in my full Rocks and Minerals Unit:

Explore more lessons from Wild Earth Lab:

If you enjoyed this post, I know you will love trying my other science and nature units in your classroom too!

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