Are you studying rocks and minerals? Mineral identification may seem challenging at first, but by using these physical properties, you can identify many common minerals! Below, you will find a list of the physical properties of minerals that will help you identify minerals.

Before we dive in: If you’re an educator planning to teach mineral physical properties, great activities and visuals are key to deepening understanding! I think you and your students will love my Minerals Mini Study, which you can also find within my complete Rocks and Minerals Unit (plus you’ll support my blog with your purchase! ❤️)

Color

Color(s) can help you identify a mineral. But proceed with caution – some minerals come in several different colors. Many different minerals are the same or similar colors as one another. For these reasons, color can be a deceptive property.

Streak

Streak is the color that a mineral leaves behind when you rub it across a streak plate. A streak plate is a hard porcelain plate for testing minerals. It is easiest to observe the color of mineral streaks if you have both a black and a white streak plate.

You can rub the mineral across the streak plate like sidewalk chalk, to see the color of the mark it leaves behind. Very hard minerals like quartz and diamond will not leave a streak at all.

Luster

Luster is a descriptive property, describing the “shininess” of a mineral. It can be described using words like “metallic”, “non-metallic”, “glassy”, pearly”, “adamantine”, “dull”, and more.

Hardness

You can think of hardness as “scratch-ability”. For example, a mineral that I can scratch with my fingernail is very soft. A mineral that can scratch glass is fairly hard. Hardness is measured on a scale of 1 to 10 with 1 as the softest and 10 as the hardest.  Refer to the Mohs Hardness Scale poster for more details.

Think of it this way: if the item scratches the mineral, then the mineral is softer than the item. If the mineral scratches the item, then the mineral is harder than the item. The streak plate can be confusing because minerals that are harder than the streak plate do not leave behind any streak.

Magnetism

Is a mineral magnetic? Find out by holding a magnet close to the mineral. This is perhaps the most straightforward physical property and is very easy to test if you have a magnet.

Acid Reaction

Carbonate minerals will react to acid. This is an acid-base reaction, similar to baking soda and vinegar. When the acid touches the mineral, you will see fizzing and bubbling.

A drop or two of acid will be enough to see a reaction. You can even use lemon juice as an acid to see a reaction in minerals made of carbonate!

Density

Density is mass divided by volume. It is a number that tells us about how much space something takes up relative to its mass.

Use a scale to measure the mass of a mineral. Then place the mineral into a beaker of water. The volume of water displaced is equal to the mineral’s volume. Density equals mass divided by volume.

If you do not have a scale, you can also roughly estimate density by holding a mineral. Does it feel unusually heavy or light for a mineral of its size?

Cleavage and fracture

How does the mineral look when it breaks? Some minerals break along one or more flat surfaces called planes of cleavage. When describing planes of cleavage, pay attention to both the number of different planes and the angle(s) at which they intersect.

A mineral that fractures breaks more randomly, appearing jagged or rounded. Conchoidal fracture is a special type of fracture, in which the mineral breaks along smooth, curved surfaces. Quartz is one example of a mineral with conchoidal fracture.

Crystal form

When a mineral forms crystals, what shape are they? Crystal form means the shapes that naturally develop during formation, rather than the way the mineral breaks.

What’s next?

Once you and your students master the physical properties of minerals, you’re ready to move on to learning how to identify common minerals. You can also teach your students about the difference between rocks and minerals and learn to identify common rocks.

Looking for specific activities? Take your lessons up a notch with my blog post on 7 rock and mineral activity ideas! You can also save time on lesson planning by purchasing my complete Rocks and Minerals Unit (more info below ↓)!

Wild Earth Lab’s Rocks & Minerals Unit:

If you are preparing to study rocks and minerals with your class or homeschool, look no further than my Rocks and Minerals Unit. It is a huge set of printable geology activities, labs, handouts, readings, posters, and much more!

Explore more lessons from Wild Earth Lab:

If you enjoyed this post, I know you will love using my earth and environmental science materials in your classroom!

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References and Further Reading

1. Earle, S. (2019). Physical Geology. BCcampus Open Education. (Chapter 2). Available: https://opentextbc.ca/physicalgeology2ed/
2. Geology.com (n.d.). What are Minerals? Available: https://geology.com/minerals/
3. GeologyScience (2018). Top 10 Minerals Used in Everyday Life. Available: https://geologyscience.com/gallery/geologic-lists/top-10-minerals-used-in-everyday-life/
4. Johnson, C., Affolter, M.D., Inkenbrandt, P., & Mosher, C. (2017). An Introduction to Geology. Salt Lake Community College. (Chapter 3). Available: https://opengeology.org/textbook/
5. Plummer C.C., Carlson D.H., & Hammersley L. (2019). Physical Geology. McGraw-Hill Education. (Chapters 1-2).

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