- HARDNESS EXERCISE A -

A SIMPLE HARDNESS SCALE
CLASSIFYING MINERAL SPECIMENS AS SOFT, INTERMEDIATE OR HARD


A SIMPLE HARDNESS SCALE. This exercise introduces you to a simple classification of hardness. Minerals may be classified as 'soft', 'intermediate', or 'hard' by comparing their hardness to commonly available materials such as fingernails and steel:
  • Minerals that can be scratched by a fingernail are SOFT (S).
  • Minerals that cannot be scratched by a fingernail but can be scratched by steel are INTERMEDIATE (I).
  • Minerals that cannot be scratched by steel are HARD (H).



What you have to do is this:

  1. After you have read these instructions (1 through 8), you will go to the Virtual Hardness Testing Lab. There you will see the Hardness Evaluation Table. A sketch (not the real thing) of the Table is shown on the right.

  2. HOW THE TABLE WORKS: The Table is designed to allow you to determine the relative hardnesses of various objects. The Table has two identical lists of materials (mineral specimens and testing tools): one list on the left (List 1) and one on the right (List 2). In the center it has boxes in which pictures of the materials being tested will appear. It also has a message box in which instructions and helpful information are provided.

  3. Examine List 1 and see if any of the minerals (identified by numbers) that you have been assigned appear on it. If an assigned mineral is present, click on the button next to it. Pressing on the button will cause a picture of the mineral to appear in the top left center box.

  4. Next, click a button next to one of the two testing tools (fingernail or steel) listed at the bottom of List 2. This will cause a picture of the testing tool to appear in the top right center box.

  5. Now press the "SCRATCH" button. Pictures of the same two materials will appear in the lower two center boxes. The softer of the two materials will have a scratch on it. A message affirming what happened will appear in the message box.

  6. For each of your assigned minerals that is present in the Hardness Evaluation Table, determine and record on a piece of paper whether its hardness is S, I or H by comparing it to the hardness of the two testing tools.

  7. 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.

  8. If they are correct, record the mineral specimen numbers and their 'hardness letters', S, I or H, in Part A of the HARDNESS EXERCISES WORK SHEET (MN-3).

NOW THAT YOU'VE READ THE INSTRUCTIONS, CLICK ON "Go to the Virtual Hardness Testing Lab"....
Go to the Virtual Hardness Testing Lab
Go to the Answer Checking Table

2010, David Leveson/Revised by G.Rocha and Michelle O'Dea