How to Identify Minerals

Hey guys,

Before i get into the mineral identifiation part, i just wanted to make sure that everyone knows the

difference between a mineral and a rock. Everything is made different elements. When one or more elements join up, this will form a mineral (They are a chemical substance). For example; the mineral sulfer is made of many sulfer atoms joining together. Whereas Silicon and Oxygen atom will form Quartz (SiO2). Rocks are simply made from minerals. Normally two or more but in cases like Quartzite there is just one. E.g. Quartz, Mica, and Fledspar make up Granite. Quartzite is made by quartz being heating and put under pressure. Therefore Quartzite is a Metamorphic rock.

Now onto the indentification.

All minerals are composed of different element/s and structures. There are 9 ways that most geologist use to indentify minerals, So ill just go through thoses and give some info and examples.

1. Color

Determining the mineral though color can either be obvious or confusing as some mineral are similar in color. For example; Gold and Pyrite look almost indentical in color. Hence Pyrites nickname, Fool's Gold.

2. Hardness

Moh's scale of hardness if used to find how hard minerals are. Really soft minerals like gypsum can be scratched by a fingernail, whereas diamonds, the hardest mineral cannot be scrtched by anything other than another diamond.

3. Luster

The luster is the way it looks with light. There are three terms used to descibe it.

Dull: No reflection

Virteous: gives off a glassy reflection e.g. quartz

Metallic: Reflects like a metal

4. Shape

Because elements link up differently the crystal structure is used to indentify. For example; we can tell apart gold and pyrite because pyrite has a cubic shape where gold is more bloby.

5. Cleavage and Fracture

This means the way the mineral will break. Mica is a good example as it cleaves in sheets. Flourite when cleaved will form a diamond shape. Because Quartz has no cleavage, it fractures unevenly.

6. Magnetism

Magnetite is the only common mineral that uses magnetism as a way of indentiying it.

7. Taste

Again, Halite, otherwise known as Rock Salt is the only mineral worth using this for. When tasting it, it will taste like salt.

8. Streak

To test a mineral's streak is to look at the mark left behind after being scratched on a porcelin tile. You may wonder, but isnt that the same thing as color? No. It is not. In some minerals the streak will be different than the color at first glance. For example, haemetite looks black, but its streak is a reddish brown color.

9. Reaction to Acid

The acid to use for this test is Hydrocholric acid. Not all minerals will react with it, but the most distinct is Calcite. It will fizz and erode the mineral. Acid rain can result in the erosion of limstone/marble structures. Another reaction with HCl is many sulphide minerals. When reacted there will be the distinct rotten egg smell of hydrogen sulphide.

10. Specific Gravity and Density.

Density (g/cm3) = Mass (g) / Volume (cm3)

Specific gravity = Weight in Air / Weight in Air - Weight in Water

Well those are the ways to find out what minerals you have. Most times geologist use more than one method to determine the mineral.

Thanks for reading,

Sabrina Kainz

#minerals #rocks #elements