---
title: "Properties of rocks"
description: "Compare and group different kinds of rocks based on their appearance and simple physical properties such as hardness, texture, and colour"
canonical: https://lightmysky.com/learn/science/properties-of-rocks-mt_R6YoRXkRxS
source: https://lightmysky.com/learn/science/properties-of-rocks-mt_R6YoRXkRxS.md
retrieved: 2026-09-12
---

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# Properties of rocks

Compare and group different kinds of rocks based on their appearance and simple physical properties such as hardness, texture, and colour

Subject: Science · Area: Earth's Systems · Ages 7 to 8
Page: https://lightmysky.com/learn/science/properties-of-rocks-mt_R6YoRXkRxS

## Ready when they can

- Describe at least three observable properties of rocks: hardness, texture, colour, grain size
- Sort a collection of rocks into groups based on chosen properties
- Compare two rocks and describe how their properties differ

## Lesson: Sorting rocks by their properties

Rocks are not all the same. You can compare rocks by looking closely and touching them. Four things to check are hardness, texture, colour, and grain size.

Hardness tells you how easy a rock is to scratch or crumble. Texture tells you if a rock feels rough or smooth. Colour is what you see, like grey, red, or white. Grain size tells you if the tiny bits inside the rock are big or small.

**Example.** Look at two rocks. Granite feels rough and has big grains you can see, like tiny specks of black, white, and pink. Chalk feels soft and smooth, and it crumbles easily when you scratch it with your fingernail.

*(drawing: How hard is each rock to scratch? Chalk is a 2, so it scratches easily. Granite is a 9, so your fingernail does nothing to it.)*

**Tip.** To test hardness, try scratching the rock gently with your fingernail. If it leaves a mark or crumbles, the rock is soft. If nothing happens, the rock is hard.

**Recap.** Check hardness, texture, colour, and grain size, then sort your rocks into groups.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Grouping Materials](https://lightmysky.com/learn/science/grouping-materials-mt_SwaNNdm_Ks)

## Opens up

- [Rock Layers & Relative Dating](https://lightmysky.com/learn/science/rock-layers-and-relative-dating-mt_EGIlsfHxb6)
- [How fossils form](https://lightmysky.com/learn/science/how-fossils-form-mt_mwirOvigWD)
- [The Rock Cycle](https://lightmysky.com/learn/science/the-rock-cycle-mt_NckKLZ3uCE)
- [Types of Rock](https://lightmysky.com/learn/science/types-of-rock-mt_NYA50DFcOO)
- [Erosion and weathering](https://lightmysky.com/learn/science/erosion-and-weathering-mt_vAP_A986IQ)
- [Rocks and soil](https://lightmysky.com/learn/science/rocks-and-soil-mt_yhhprm7dZK)
- [Fast and slow Earth changes](https://lightmysky.com/learn/science/fast-and-slow-earth-changes-mt_ZJu8s-Q1xa)