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Help with science fair

Posted: Fri Nov 16, 2007 1:08 pm
by Mary Todd Brown
My daughter is during a science project about rocks. “Which Rock Is Harderâ€

Posted: Fri Nov 16, 2007 2:08 pm
by Craig_Bridge
If you do a search for "rock hardness scale" using your favorite search engine you will get some entries that have "Mohs Scale of Hardness" one of which is

This scale is based on what can scratch what and goes back to the early 1800's and Frederick Mohs.

The problem with impact tests or drop/shatter tests is they tend to measure how brittle a substance is. Things can be quite hard (scratch resistant) and be extremely brittle. Glass is a good example.

Posted: Mon Dec 03, 2007 11:47 am
by Mary Todd Brown
Thanks craig for the information. I purchased the kit and a collection of all three types rocks. However, I don't have a diamond, ruby,or opal to conduct the hardness experiment so is there there some other method I may use to prove my point?

I don't know how to proceed with what I have. I have to conduct an experiment that I can show on my presentation board. Please give me an idea.


Posted: Mon Dec 03, 2007 1:09 pm
by Craig_Bridge
I would talk a science teacher and look up gemologists and/or minerologists in the phone book and see if you can find somebody who has some industrial grade diamonds, ruby, and opals that would be able to help you with your project.