Minerals

Minerals

4 General Characteristics
     (1) They are solid (can't be a liquid or a gas)
     (2) They are inorganic (nonliving)
     (3) They are formed by nature (not formed by man or woman)
     (4) They have a crystalline structure (composed of crystals)

What Is A Mineral?

Mineral: A naturally formed, inorganic solid with a crystalline structure.

As you can see from its definition, we pretty much define the term mineral by listing the 4 general characteristics of minerals. Look what I mean...

"A naturally formed, inorganic solid with a crystalline structure.

Can you see the four general characteristics of minerals in this definition? I made each a different color so that they are easier to see.

A Closer Look...
This definition is great, but some of those words aren't really words we use everyday. For instance, check out the term crystalline structure and the term inorganic. You may not see those terms everyday. Let's take a closer look at each of the "4 characteristic terms" to make sure that we understand them.

Naturally Formed
Hmm...Naturally formed. Interesting! What this is referring to is an object that is formed by nature. It cannot be formed by humans. For example, in class I had a hacky sack in my hands. I know that it was formed by humans. The big giveaway was that it said "efootbag.com" on it. Actually, I knew it was made by humans before I read the label. I could just tell... My hacky sack could not be a mineral because it was not naturally formed. A mineral must be formed by nature.

Inorganic
I've heard of organic things. You may have seen organic food in the grocery store. But what's inorganic? Inorganic simply means not-organic. Okay. Well then what's organic? Here's a basic definition for the term organic: formed or composed of living organisms. So inorganic would mean just the opposite: formed or composed of non-living organisms. In a nutshell, inorganic means it's composed of non-living things. A mineral must be made of non-living things.

Solid
Ah...solid. This is a somewhat more familiar term. A mineral must be a solid. It cannot be a liquid or a gas. Remember the three states of matter? Solid, liquid, and gas. In class, we used a "water" example. I turned on the faucet and pointed the hose up so the water shot up in the air. We could all see that the water coming out of the faucet is a liquid (I hope we knew that already.). Therefore, the water coming out of the faucet cannot be a mineral. A mineral must be a solid!

Crystalline Structure
This term is perhaps the term we have used the least in the past. Although, we have been using it quite often lately in our class. The term crystalline structure for our purposes, simply means that it is composed of, or made of, one or more crystals that have a repeating inner structure of atoms that is often reflected in the shape of the crystal. We worked on a class activity where students formed model crystals out of paper. After we formed our crystals we taped our model crystals together to form a larger mineral. With these large "model" minerals it was easy to see all of the crystals that went together to form the mineral.
Watch the "Building Crystals and Minerals" Video hi quality | low quality

What Are Crystals Made Of?

If minerals are made of crystals, then what are crystals made of? Good question! We talked about this briefly in our class. Crystals are made of a tiny substance called elements. Wow! So here we have minerals that are made of crystals...And we have crystals that are made of these tiny elements. And guess what? There's more! Elements are made of even smaller things called atoms. So let's review that. Minerals are made of crystals, crystals are made of elements, and elements are made of atoms. Wow! That's pretty cool. There sure is a lot more than the naked-eye can see that goes into making these crystals and minerals. Did you think there would be this much?

5 Properties To Consider When Identifying Minerals

Once you've determined that an object is a mineral, the next step is to find out what kind of mineral it is. There are certain properties to look at in order to identify minerals. Some of these properties are listed below.
(1) Color

(2) Luster

(3) Streak

(4) Cleavage or Fracture

(5) Hardness

Color...
Color is self explanatory. When you describe the color you simply state the color: It's blue; it's gray, it's a yellowish orange, etc. Be as descriptive as possible. If there is more than one color present on the mineral, be sure to take note of it.

Luster...
Luster is a description of the way light behaves when it hits the surface of a crystal. For example, you could describe some minerals' luster as being very dull, while others you could say are very shiny and reflective. Below is a short list of some of the words that you may use to describe an object's luster.
- Dull a non-reflective surface
- Shiny the mineral is shiny and reflects light
- Transparent can see through the mineral
- Translucent light goes through the mineral
- Metallic looks like metal.

Keep in mind that there are many more words that you can use to describe luster. Be creative in your description.

Streak...
When a mineral is rubbed firmly across a streak plate, it leaves a mark, or a streak, of powder. When describing a mineral's streak, you simply state the color of the streak. For example, if you were streak testing the mineral quartz, you would find that it leaves a white streak. In your description you would write, "This mineral leaves a white streak." It's as simple as that!

Cleavage or Fracture...
In our first lab identifying minerals, we talked about cleavage and fracture as being "how the mineral breaks apart." So, a simple definition of this property is simply, Cleavage and Fracture describe how a mineral breaks apart. More technically speaking, cleavage and fracture are two separate ways to describe how a mineral breaks apart. For example, a mineral is said to have cleavage if when it breaks it forms a flat surface. A mineral is said to have fracture if when it breaks it forms a non-flat surface.

Just remember that cleavage and fracture both describe how a mineral breaks apart.

Hardness...
Hardness simply describes how hard a mineral is. This can be tested by scratching the mineral. Check this out... A mineral can only be scratched by something that's harder than it. A hard mineral can scratch a soft mineral, but a soft mineral cannot scratch a harder mineral. So, we can actually test hardness by simply seeing which minerals scratches another.

French mineralogist Friedrich Mohs developed a scale to test hardness. Below is Mohs Hardness Scale...

1. Talc
2. Gypsum
3. Calcite
4. Fluorite
5. Apatite
6. Orthoclase
7. Quartz
8. Topaz
9. Corundum (ruby and sapphire)
10. Diamond

When you describe how hard a mineral is, you can simply state a number on Mohs Hardness Scale.