Some metal content on the following site:

http://encyclopedia.thefreedictionar...neral+hardness

I was surprised to see hardened steel is rated as being harder than glass.
I presume this is hardened steel that has almost no structural use
whatsoever due to being so brittle.

Regards,
Joe Agro, Jr.
(800) 871-5022
01.908.542.0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com

V8013-R