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Mineral Basics


    Minerals are the basic building blocks of rocks. Most people only know the famous or the pretty ones and don't realize the importance they have. The reason granite is so hard is because of the minerals it is composed of, or the reason marble is so soft and easily carved. Since minerals have specific structures they each have unique properties that when combined are used to identify them.

Definition of a Mineral - A mineral is a naturally occurring, homogeneous inorganic solid substance having a definite chemical composition and characteristic crystalline structure, and hardness (dictionary.com).

Mineral Websites


Amethyst Galleries                   Windows To The Universe                 Mindat          Minerals.net

   Amethyst Galleries              The University Corporation of                   The Mineral and

                                                Atmospheric Research Science                 Location Database 


MEC Logo                                Molecule of the Month 


 University of Colorado: Mineral Structure Data


Identifying Minerals


Listed are the main defining characters used in identifying minerals


1. Color                                    3. Streak                            5.Cleavage                               7.Other (Taste, Acid Reaction, etc.)

2. Hardness                               4. Luster                            6. Specific Gravity                                                                         


1. Color


Color is the most useless way of identifying minerals, although it is also the principle reason people love them.


Often several minerals contain the same color

Fluorite  Amethyst  Sphaerocobaltites  SugilitePurple Chalcedony

Some Purple Minerals



Or the same mineral has several different colors

Amethyst  Citrine  Crystal Quartz  Rose Quartz  Smoky Quartz

Variations of Quartz


2. Hardness

Moh's Hardness Scale

Minerals                                         Tools              

                                                                                                 Softest (Easiest to scratch)

1 - Talc                                                                


2 - Gypsum                                                                

                                                                 2.5 - Fingernail

3 - Calcite                                                                

                                                                 3.5 - Copper Penny

4 - Fluorite                                                                

                                                                 4.5 - Steel Nail

5 - Apatite                                                                

                                                                 5.5 - Glass Plate

6 - Orthoclase                                                                

                                                                 6 - Ceramic Tile

7 - Quartz                                                                


8 - Topaz                                                                


9 - Corundum                                                                


10 - Diamond                                                                  

                                                                                                             Hardest (Most difficult to scratch)


3. Streak


Streak Test



Example of the color of a mineral does not effect the streak

Red Hematite     Silver Hematite

Two samples of Hematite, one silver (left) one red (right).

Both will give a characteristic bright red streak.


Hematite Streak


4. Luster


 - Looks like metal.

For Example - if it looks like a gold or silver ring it is probably metallic


Gold Metallic                          Silver Metallic



- Does not look like metal.

- Can be broken into several different categories.

- The most important category is that it is a nonmetal, the subcategories are not usually used.



      Pearly                Glassy (Vitreous)               Dull                       Waxy                          Earthy                            Greasy    

Pearly           Glassy           Dull           Waxy           Earthy            Greasy


5. Cleavage


     No Cleavage                                           Conchoidal Fracture      

        Breaks into just a random mess                  Shatters similar to glass with curved sharp pieces

Red Hematite                              Shattered Glass



     1 direction                                                                  2 directions                   

                                                                sides @ 90°                               sides not @ 90°

1 Direction Cleavage                    2 Directions Cleavage at 90                 2 Directions Cleavage not at 90

           Breaks into thin sheets                Elongated box with broken ends         Crushed box with broken ends


3 directions

sides @ 90°                                    sides not @ 90°     

3 Directions Cleavage at 90                    3 Directions Cleavage not at 90


6. Specific Gravity


7. Other