How to Read a Mineral Chart

If you have a mineral collection, you will likely need to read the mineral chart as a part of your hobby. The mineral chart depicts specific characteristics for each type of mineral, and you can use it to help identify the pieces in your collection.

Difficulty: Moderate

Instructions

Things You'll Need:

• Streak plates
• Moh's scale of hardness
• Eye protection
• Mineral chart
• Geologist's hammer
• Minerals

Read a Mineral Chart

1. Note the mineral name. Its chemical formula or representation of elements appears alongside the name.

2. Check the color column. Minerals come in an almost limitless array of colors like white, blue, red, light grey, pink, green or yellow.

3. Look at the mineral's streak. The mineral's streak appears as a finely pulverized color achieved by rubbing the specimen across a streak plate. Streak plates are unglazed, ceramic or porcelain tile used for mineral identification.

4. Locate the mineral's hardness. Moh's hardness scale functions between 1 for soft minerals (like talc) to 10 for hard minerals (like diamond).

5. Read each mineral's recorded breakage pattern. Some minerals fracture, while others form a cleavage.

6. Find the last category, the mineral's use and purpose. For instance, topaz is used for jewelry, talc is used to make paper and powder products and calcite is used in cement or other building materials.

Identify Minerals Using the Chart

7. Note the mineral's color. Each mineral has a special color or group of colors to which it belongs. For example, malachite is always green, but quartz can appear in a range of tones from smoky to rose.

8. Perform a streak test. The color of the streak always remains the same, even if it is from a mineral which can appear in different colors. All types of quartz contain a white streak.

9. Record the mineral's hardness using the Moh's scale for hardness. Scratch an unknown sample with known mineral samples (whose hardness appear on Moh's scale). The mineral will either scratch or be scratched, which will lead to its hardness.

10. Break the mineral using a geologist's hammer. It will either form a cleavage, which appears as a clean break along planes of weakness, or fractures, which are jagged and uneven pieces.

Tips & Warnings

• If you do not have access to Moh's scale, you can use common household items such as a fingernail (2.5 hardness), a penny (3.5), glass (5.5), a steel knife (6.5) and an emery cloth (8.5).
• Other traits beyond what appears on the mineral chart can reveal a mineral's identity. You can also measure specific gravity, crystallization, transparency and luster.
• Wear eye protection when breaking minerals with a hammer.