"Lana" wrote in message ...
btilley wrote:

Can anyone recommend a good home test kit to test for hardness?
I bought a $10 kit at Home Depot, but I got only two samples out of it,
and it didn't seem to be as precise as I would like.

No need for a kit. Moh's scale is universally accepted and requires no
special tools or equipment, but you do need up to 10 materials:

1 Talc Fingernail scratches it easily.
2 Gypsum Fingernail scratches it.
3 Calcite Copper penny scratches it.
4 Fluorite Steel knife scratches it easily.
5 Apatite Steel knife scratches it
6 Feldspar Steel knife doesn't scratch it easily, but scratches glass.
7 Quartz Hardest common mineral. It scratches steel and glass easily.
8 Topaz Harder than any common mineral.
9 Corundum It scratches Topaz
10 Diamond It is the hardest of all minerals.


Tell me why you need to change the diamond stylus of a phonograph record?
Diamonds are the hardest substances known to man, and surely much harder
than vinyl. Why would a phonograph needle ever wear out?