Friday, February 16, 2018

Make Your Own Mineral Identification Kit

    My 7 year old daughter has been studying geology the last few weeks. We've taken several hikes and nature walks to try to find and photograph neat geologic features. We've also collected a few samples of cool rocks and minerals to try to identify.  

In this post I will explain how to put together your own mineral identification kit and how to use it to identify minerals you find on your adventures.

Make Your Own Mineral Identification Kit from the Barefoot Mom

   First you will need to gather up the supplies you will need (most of it is stuff you can find around the house):
-A small notebook
-A pencil
-A coin
-An iron nail
-A piece of glass (an old pocket mirror or works well)
-A ceramic tile
-A small water tight bottle or container
-Some vinegar
-A magnet 
-A magnifying glass
-A dropper (optional) 
-Rock and mineral guide (optional) 
-A small container or bag to keep it all in

   Fill the small water tight bottle with vinegar, this will be used for the acid test. Then put all your supplies into your bag or container. Your mineral identifying kit is now ready to use. Now you just have to go out and find some minerals or rocks to identify.

Rock hunting

   Once you've collected some minerals and rocks, you can get started identifying them. There are four tests you can do with the supplies in your kit. The results of these tests plus some simple observations will help you identify the mineral or minerals present in your sample.

The Hardness Test

     For the hardness test you will need your sample(s), the ceramic tile, the mirror, the iron nail, the coin, and your fingernail. The idea behind this test is a material harder than another will scratch the softer material. Using materials with a known hardness can help you find out the hardness of yoir sample. 

Moh's Hardness Scale for mineral identification

   Start with your fingernail and see if you can scratch your sample. Your fingernail has a hardness of about 2.5-3. If you can scratch your sample with your fingernail, your sample is compsed of fairly soft minerals and has a hardness of less than 3. Record your results.

   If you cannot scratch your sample with your fingernail, move onto the iron nail. If you can scratch your sample with an iron nail but not your fingernail, it has a has a hardness of about 3-4. Record your results.

   If you cannot scratch your sample with an iron nail, move onto the glass. Since you can't scratch your sample with a mirror safely, see if your sample can scratch it. If your sample does not scratch the glass or mirror, it has a hardness of about 5. Record your results.

   If your sample can scratch the glass or mirror, move onto the ceramic tile. If your sample cannot scratch the ceramic tile it has a hardness of about 6-7. If it does scratch the tile, it has a hardness of 7 or higher. Record your results.

Identifying minerals: hardness test

The Streak Test

    To perform the streak test you need your sample (or samples) and the ceramic tile. This test is simple, you just run your sample over the ceramic tile to observe what color streak it leaves. Most minerals leave a white streak but some leave very distinct colors like yellow, green, or brown. Skip the streak test for minerals with a hardness higher than 7, as they will only scratch tile, not leave a true streak. Record your results in your notebook.

Identifying minerals: streak test

The Magnetic Test

   The magnetic test is easy. Just hold the magnet to your sample and observe whether or not there is any magnetic attraction. Record your results.

The Acid Test

   Some minerals, like calcite, react with acid. For this test, drop a few drops of vinegar onto your sample and carefully observe to see if there are any gas bubbles produced. Record your results.

Identifying minerals: acid test. Some minerals like calcite react with acid.

   Once you've finished performing your tests, your ready to move onto actually identifying your sample(s). Using your rock and mineral guide or an online data base like this one at Collector's Corner, you can now identify your sample using the results of the tests and some simple observations like color and whether or not your sample is metalic. If your sample is a rock instead of a pure mineral, it is composed of two or more minerals. You will need to start by identifying what minerals your rock is composed of and then look up common rocks composed of those minerals. Collector's Corner has a good rock databse here.

Enjoy your mineral and rock hunting!

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