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:
-Streak Plate OR Unglazed Tile
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:
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:
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.
Second Prize in the
Explore Science Contest 2017
Runner Up in the
Outside Contest 2017
Runner Up in the
First Time Author Contest