Minerals and Moh's hardness scale

Complete the crossword, then click on "Check" to check your answer. If you are stuck, you can click on "Hint" to get a free letter. Click on a number in the grid to see the clue or clues for that number.
    1          2      
                
3           4         
                
5       6             
                
    7              
   8               
   9               
                
         10   11        
                
     12             
                
         13         
                
    14       15         
                
                
                

Across:

3. Green varieties of this mineral are called emerald. One of two minerals with a hardness of 8.
4. This semi-precious gemstone has a hardness of 8.
5. Made of consistently the same chemical elements. A requirement of minerals.
7. The main industrial use of this mineral is to make wallboard or sheet rock for the interior walls of houses and buildings. It is soft and easy to work with. It is also used to make plaster of Paris.
9. Tan, pink or white mottled mineral with a hardness of 6. Together with quartz, makes up most of the continental crust. It contains K, Al, Si, and O.
10. In order to be a mineral, a substance must be _______. Not man-made.
12. In order to be a mineral, a substance must be ______ . Not from the living parts of an animal. Not based on carbon.
13. The hardest mineral. Sometimes referred to as ' a girl's best friend'.
14. This mineral causes double refraction when placed on an image. It used to be used in making of lenses. It fizzes when acid is placed on it. It helps to tie up carbon dioxide from the atmosphere. It makes up the rock limestone.

Down:

1. To be a mineral, substances must be in this state of matter.
2. This mineral is one of the most common on earth. It hase a mineral hardness of 7. Made of two of the most common elements on earth.
5. This purple or green mineral has a mineral hardness of 4. It is made with fluoride a chemical that makes your teeth harder and resistant to cavities.
6. In order to be a mineral a substance must be __________. Even if they are so small that you cannot see them. Quartz ______ are always 6-sided and pointy.
8. Red varieties of this mineral are called ruby. It is the second hardest mineral.
11. This mineral is of olive green, or yellowish green and has 6 sided flat topped crystals. It has a mineral hardness of 5. It can be used as a fertilizer because it has phospate a plant nutrient.
15. This mineral is so soft it used to be used in baby powder. The mineral feels almost greasy and has a hardness of 1.