How to EASILY Identify Rocks and Minerals

Have you ever found a rock and wondered what it was? Or maybe you have an old collection but can't remember what hidden treasures you actually have? Well, you're in luck. By doing a few simple tests you can discover how valuable those useless chunks of rock really are!

Step 1: Gathering Your Materials

This process can be as simple or complex as you want to make it. The bare minimum things you'll need for this project are a mineral specimen and your eye!

However, these are the supplies and materials we'll need to collect the needed data in this instructable:

-Mineral/Rock Specimen

-A penny

-Steel Blade

-Streak Plate OR Unglazed Tile

-Scale

-Water

-Graduated Cylinder

-Old toothbrush

-Paper

-Pencil

Step 2: Creating a Data Table

Using the pencil and paper, create a table similar to the one above.

The table should have spaces for:

-Specimen Name

-Color

-Hardness

-Streak

-Luster

-Specific Gravity

The first thing I like to do is give my specimen a fun name. You can make it as fun as you want, or simply call it specimen #1. I like to give it a name I'll be able to identify it with in case I have to stop and come back to the tests.

Once you have your data table made, you're almost ready to start collecting data!

Step 3: Cleaning Your Specimen

This is the most important step. By using a simple toothbrush and water, you should be able to clean any dirt and debris off of the specimen. Dirt and debris can make your specimen an entirely different color, shape, and shine. It's very important that your rock or mineral is clean before you begin any tests.

Step 4: Identifying Color

As easy as it sounds, this part can be tricky. Some minerals, like beryl, come in red, pink, yellow, and green. Some minerals, like bismuth and fluorite, can have a multitude of colors! Record all colors you see on the specimen in the data table.

Step 5: Identifying Luster

Luster is essentially how light reflects off of your specimen. There are several different types of luster, and this website does a great job of explaining them. In the photo above, from left to right, the specimens' lusters can be described as:

-Greasy

-Silky

-Dull

-Glassy

-Metallic

Record the luster and you're ready to move on to the next step!

Step 6: Measuring Hardness

As hard as it sounds (bad pun, I know) this step is quite easy.

First, take your specimen and gently scrape your fingernail with it.(NEVER scrape your specimen, this can cause damage to it. Always be sure the mineral is doing the scraping.)

If your mineral scrapes your fingernail, continue to scrape a copper penny. If your mineral does NOT scrape your fingernail, record the hardness as less than 2.5.

If your mineral scrapes the copper penny, continue to scrape a steel blade. If your mineral does NOT scrape the penny, record the hardness as 2.5 <specimen< 3.

If your mineral scrapes the steel blade, record your hardness as more than 5.5. If your mineral does NOT scrape the blade, record the hardness as 3 <specimen<5.5

This is the simplest way to perform this test. It gives you a nice range of hardness which will eliminate many potential minerals.

Step 7: Identifying Streak Color

The Streak Color is the color of the mineral in powdered form. The color of the mineral powder is not always the color of the mineral itself. By using either a streak plate, or an unglazed tile, you can find your specimen's streak color.

Gently drag the mineral along the plate or tile as seen in photo one. This will leave a streak as seen in photo two. Depending on your specimen, it might be harder than the plate and not leave a streak. Or your mineral could leave a white streak. Make sure you carefully examine anything left behind on the streak plate.

Record your data and move on to the next step!

Step 8: Finding the Specific Gravity

Specific Gravity is just a fancy word that means density. This step will knock out lots of potential minerals your specimen could be.

First you'll need to weigh your specimen.

Next, find the volume. To find the volume, fill the graduated cylinder up with water. On scratch paper, record how much water is in the cylinder. Then gently place your rock into the cylinder. Now record how much "stuff" is in the cylinder. Take the larger amount and subtract the smaller amount from it. This will give you the volume of your specimen.

Finally, using the formula in photo two, calculate the specific gravity.

Record the specific gravity and move on to the next step!

Step 9: Take Any Additional Notes

Does your specimen have a funny smell? Although I don't recommend eating any rocks, does it have a salty taste? Is your specimen magnetic? Do you feel a sudden rush of adrenaline and the urge to fly when you touch your rock? Some minerals have certain properties that other minerals don't have. Record any other notes you have in the last row of your table.

Step 10: Identify Your Mineral

Finally! After all these tests you're ready to identify your specimen.

This website allows you to filter minerals based on your findings. You can always of course simply google based on your findings.

(Example: "Minerals with specific gravity of 2.7")

Thank you for taking the time to read my instructable. I hope it helped you identify any rocks and minerals in your possession.

Comments

[NikSplodge]

Great, really clear and helpful, thank you!

[PrettyGoodMonsters]

Holy smokes, thank you so much for this! I have a huge bag of rocks & I was so lost as to how to go about identifying what each of them were. You made this so easy!

[bcjack12]

W
I’ll someone identify this rock as to what type it is please reply

[tianat70]

is there a stone that is transparent, completely clear in water and clouds up when it drys?

[Dark Solar]

It's not a stone but sea glass does exactly what you described. Diamonds have the same refractive index as water so maybe a tumbled diamond? Oh, and halite; technically a rock...just not the best of rocks.

[Artuino]

I'm always fond on minerals. I love its natural color and structure. thanks. nice instructable.

[Gailsy]

Nice Instructable! I used to examine minerals and rocks with my grandparents. This brought back some wonderful memories. I'll have to try this with my grandchildren when they get a bit older! Thanks for the Instructable.

[UNSEPARABLE TECHSCIENTIFICS]

EXCELLENT SCIENTIFIC WORK MY FRIENDS!!!!

: D

[charles543]

Maybe I'm missing something. The text talked about using the website to identify stones. Where is that website?

[TheodoreK17]

http://www.minerals.net/Minerals/A.aspx

[Drake88]

Good guide! I only have one small thing to say - if any rocks happened to picked up from large piles near old site of human habitation(ghost towns) be VERY careful about the taste test. Some of those old ghost towns happen to be built on or near mine sites, and some of those sites could have possible chemical toxins around them from the mining. Just a thought......

[KVSBUNNY]

wow, no, I mean WOW! We're going to the southwest in a little less than 2 months and I know I 'll be picking up tons of rocks. where can I get a streak plate? Thanks!

[gizmologist]

If you can't find an "official" streak plate, the back side of a white ceramic tile works exactly the same. That's all a streak plate is.

[Dark Solar]

I actually prefer using the back of a ceramic tile because it's already divided up into squares/hexagons (having a fine-nib magic marker helps too) that are easy to label and keep ordered.

[johsheldon]

https://www.amazon.com/White-Streak-Plates-set-10/dp/B004NEIRC2

I just buy mine off Amazon. Lots of teaching supply stores have them. If you can find a teaching supply store, I highly suggest looking there.

[gizmologist]

Very nice basic tutorial! There are good field guides for those places without an internet connection. A pocket knife, fingernail, and piece of quartz for hardness, a small magnifier, and a small streak plate complete the field kit.

[Michal Choma]

nice, i looking for manual how to indentify minerals. What should be interesting, make same concept for rocks! We know some basic rocks, so do it for them, identify a little bit different features, because rock consist of more minerals.

[Swansong]

That's neat, I hadn't heard of that site before :) My husbands' aunt love picking up stones out in Montana.

[johsheldon]

Thank you! I too enjoy collecting rocks!

[Michal Choma]

nice instructables, I study geography, so it helps. Also, what about rocks? Website which you write at end, doesnt allow rocks. Basically rocks = 2 or more minerals mixed.