When we began studying mining, we kept hearing the word ‘mineral’ all the time.  Mining takes rocks, gemstones, and minerals out of the ground.  We thought it would be a good idea to find out what a mineral really is.  The dictionary says that a mineral is:  “a naturally occurring … solid substance having a definite chemical composition and characteristic crystalline structure, color, and hardness.” [American Heritage Dictionary]  This means that minerals are formed by nature and are solid.  They are made up of chemicals that form crystals. They are identified by the characteristics that are in all pieces of the same mineral, no matter where it's found. 
     Some minerals have just one mineral in them, like gold.  These are called elements and are on a list called the Periodic Table of Elements.  Most minerals are a combination of these elements.   An example of this is: 

Zinc [Zn] + Sulfur [S] + Iron [Fe] = Sphalerite

If you look at the Periodic Table of Elements that is linked above, you will see how many different elements there are.  This makes lots of different combinations and lots of different rocks, minerals, and gemstones.  Most minerals are a combination of two or more different elements. 

Minerals that are included on our site:

Figuring Out What Mineral it is!

    Since there can be so many combinations of elements to make the different minerals, scientists had to find ways to figure out which minerals they were.  Over 3000 minerals have been discovered. Scientists who study minerals are called mineralogists.  Mineralogists had to find ways to always recognize a mineral.  They found out that all minerals have properties.  This means that a mineral has characteristics that are the same each time the mineral is tested.  For an example, we will use calcite. A mineralogist has two minerals in front of him.  Both are white, neither is magnetic, but one of them is transparent [can be seen through] and one is opaque [cannot be seen through].  Having a list of properties or characteristics of each mineral allows the mineralogist to decide that they are not the same and that the transparent one is calcite.  He can decide this because calcite has been studied a lot and is not opaque.
     These are the characteristics or properties of minerals:

• Luster:  What does the surface of the mineral look like?  It could be metallic or non-metallic.  It either shines [or has a dull shine] like you expect in metals.  An example of this is aluminum.  The mineral might be non-metallic.  There are lots of words to describe the surface shine of a non-metallic mineral.  Some are: waxy [like a candle], dull [is not shiny], or pearly [shimmery or iridescent].  There are a lot of other words that we included in the actual mineral descriptions and we explained each one. 

• Hardness:  The Mohs’ Scale of Hardness is used to explain how hard a mineral is.  Hardness ranges from 1 [soft] to 10 [hard].  Since a mineral can only be scratched by something that is harder than it is, its place on the Mohs’ Scale is usually explained with a description of the thing that will scratch it.  A mineral that is higher in number on the scale, will scratch anything that has a lower number.  For example, Topaz that is an 8 on the scale will scratch Talc that is a 1.  On the other hand, Topaz won't scratch a diamond that is a number 10.  Gemstones are always harder minerals.  Even though there are other pretty minerals, they are not used as gemstones unless they are hard.  Gemstones cost a lot of money and if they were soft, they would break easier.  The gemstones couldn't be used for jewelry if they were soft.  On the chart below, the gemstones are higher numbers since they are harder.

• Color:  Mineralogists know what colors the minerals usually are.  An example of this is the diamond.  After studying diamonds for years and years, scientists can say, from experience, that diamonds are usually colorless, yellow, or grey.  They also know that they can be other colors, too.  Color is only one of the characteristics that they use to identify a mineral.  Because there are differences in minerals [like colors], mineralogists don’t depend on just one of the characteristics to figure out which mineral it is.  They use them all.

• Streak:  This is the color of the dust that is left after you grind up a mineral.  In school, we usually use something called a streak plate because we can’t just pound all the minerals into dust to test streak.  Instead, we rub the mineral on the ceramic plate which has a hardness of 7.  Any mineral that is softer than 7 will leave a little dust on the plate when it is rubbed on it.  The color of the dust is a mineral characteristic.  Sometimes the color of the dust is different than the color of the mineral. 

• Cleavage: Cleavage is how a mineral splits.  Some minerals split evenly in one direction into sheets, like Mica.  Other minerals always split in three or four directions.  The mineral does the same split every time.  If you had 2000 chunks of Mica, every one would split in one direction into thin sheets.  Because it happens every time, it is a way to identify a mineral.

• Fracture:  When a mineral shatters, it doesn’t always break evenly like cleavage.  It fractures into different shapes depending on what mineral it is.  Some have jagged edges, some have smooth ones, and some break into grains or uneven chunks.  Mineralogists expect certain minerals to fracture into jagged pieces because they always do.

• Magnetism: Mineralogists will check to see if the mineral is magnetic or not.  If it is attracted to a magnet, it is magnetic.  If it is not attracted to a magnet, it isn't magnetic.  This is another way to identify a mineral.

• Specific Gravity: This is the weight of the mineral compared to the weight of water.  This tells the scientist how heavy a mineral is.  For example:  platinum is very, very heavy.  Mineralogists are able to narrow down what the mineral is based on its weight.  Metals are heavier than regular minerals.

• Crystal System: There are lots of different crystal formations.  A mineral always has the same one.  With each mineral, we named the crystal system with its proper name and then our team artist drew a picture of what the crystal looks like.  We felt this would be easier to understand than axes, prisms, and symmetry.

• Transparency: Most minerals are transparent, translucent, or opaque.  Transparent means that light can shine straight through it.  An easier description is that you can see right through it like you do with window glass.  Translucent means that light can shine through it but its path is changed when it exits.  An easier description is that it is blurry to look through.  Opaque means that light won't go through it at all.  Our easier description is that you can't see through it at all.