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. ... In 1822 he this method of mineral hardness and scratch resistance.

What will scratch glass?

Hardened steel, such as a file, can scratch glass. Titanium, chromium and even sapphires or rubies can scratch glass, while aluminum or a butter knife blade may not.

Does fluorite scratch easily?

A minerals rating on the hardness scale is determined by a scratch test. For example the diamond is the hardest mineral because no other mineral on the scale is able to scratch it. ... 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.