Mary Todd Brown
Posts: 2
Joined: Thu Nov 15, 2007 2:52 pm

Help with science fair

Postby Mary Todd Brown » Fri Nov 16, 2007 1:08 pm

My daughter is during a science project about rocks. “Which Rock Is Harderâ€

Craig_Bridge
Former Expert
Posts: 1297
Joined: Mon Oct 16, 2006 11:47 am

Postby Craig_Bridge » Fri Nov 16, 2007 2:08 pm

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 http://www.bestcrystals.com/hardness.html

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.
-Craig

Mary Todd Brown
Posts: 2
Joined: Thu Nov 15, 2007 2:52 pm

Postby Mary Todd Brown » Mon Dec 03, 2007 11:47 am

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.

Catherine

Craig_Bridge
Former Expert
Posts: 1297
Joined: Mon Oct 16, 2006 11:47 am

Postby Craig_Bridge » Mon Dec 03, 2007 1:09 pm

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.
-Craig


Return to “Grades K-5: Life, Earth, and Social Sciences”