- HARDNESS EXERCISE C -
USING THE MOHS SCALE TO DETERMINE THE HARDNESS OF NON-MOHS MINERALS
|INTRODUCTION: In Exercise
B, you determined the relative hardnesses of the minerals that define the
points on the Mohs Scale. The Mohs hardness of any other mineral may be established
by determining between which two Mohs minerals the hardness of the mineral
lies. In the example shown on the right, mineral 'X' is harder than Mohs
Scale mineral 7 and softer than Mohs Scale mineral 8. It may have a value
such as H = 7.5. |
It is also possible for a non-Mohs
mineral to have a hardness exactly equal to the hardness of one of the Mohs
Minerals. In that case, its hardness will be a whole number.
the Mohs hardness of an unknown may be an important aid to identifying it.
For example, the minerals apatite and beryl may be very similar in appearance,
but apatite has a hardness of H = 5, while the hardness of beryl is 7.5 to
8. Thus, a simple hardness test may serve to distinguish them.
What you have to do is this:
NOW THAT YOU'VE READ THE INSTRUCTIONS,
CLICK ON "Go to the Virtual Hardness Testing
- After you have read these instructions (1 through 4), you will go to
the Virtual Hardness Testing Lab. There you will see the Hardness Evaluation
- HOW THE TABLE WORKS: A sketch (not the real thing) of
the Table is shown on the right. The Table has two identical lists of mineral
specimens and testing tools: one on the left (List 1) and one on the right
(List 2). The Mohs mineral specimens are marked with asterisks *.
- On the real Table, you will click on the buttons to choose a different mineral from each list. Pictures of the two minerals will appear in the top two boxes.
- Then you will press the "SCRATCH" button. Pictures of the same
two mineral specimens will appear in the lower two boxes. The softer of the
two minerals will have a scratch on it. A message will appear in the message
- WHAT TO DO: For all of the minerals
that you have been assigned that appear on the Hardness Evaluation Table,
follow steps (a) through (d). Keep a record of your results (the numbers
of the specimens tested and their hardnesses) on a piece of paper.
- Test the specimen against each of the Mohs minerals. The Mohs minerals are marked with asterisks *.
- If there is a Mohs mineral which it doesn't scratch and which doesn't scratch it, then they have the same hardness.
determine between which two Mohs minerals the hardness of the specimen falls.
(For example: Specimen # 16 is scratched by # 6* (H = 3) and all harder Mohs
minerals; but it scratches # 12* (H = 2) and all softer Mohs minerals. Thus,
the hardness of Specimen # 16 falls between H = 2 and H = 3.
a hardness number to your choice. (For example: Specimen # 16 can be assigned
a hardness greater than 2 but less than 3, such as H = 2.5.)
- After you have finished testing, return to this page. Enter
your results in the 'interactive' Answer Checking Table (see the purple button
below) to see if they are correct
- If they are correct, record the mineral specimen numbers and their Mohs hardnesses in Part C of the HARDNESS EXERCISES WORK SHEET (MN-3).
Go to the Virtual
Hardness Testing Lab
© 2010, David Leveson/Revised by G.Rocha and Michelle O'Dea