A minerals rating on the hardness scale is determined by a scratch test. ... Since Fluorite is a 4 on the scale it means that fluorite can scratch all the minerals below it but not be scratched by them. Also if a penny can scratch a mineral it rates a 3, a fingernail is 2.5, knife blade 5.5, glass 5.5 and steel file 6.5.

What can fluorite be scratched by?

It can be scratched by topaz, corundum, and diamond. Quartz will scratch minerals that have a lower number on the scale. Fluorite is one…. Mohs Hardness Scale.

Which mineral could be scratched by a penny but not by a fingernail?

If it doesn't scratch, next try a copper penny. If you are able to scratch your specimen with the penny but not with your fingernail, it has a hardness between 2.5 and 3.5. If the specimen does not scratch with a penny, try a knife blade or glass. A diamond can only be scratched by another diamond.