What Is a 3 on Mohs Scale

A penny has a hardness of 3.0 – slightly harder than your fingernail. So, if you can’t scratch the specimen with your fingernail (H=2.5), but a penny does the job, you immediately know that it is at least as hard as calcite (H=3).

How hard is 2.5 on Mohs scale?

So, a diamond is the hardest substance known to man. On the Mohs scale, fingernail has hardness 2.5; copper penny, about 3.5; a knife blade, 5.5; window glass, 5.5; steel file, 6.5. Using these ordinary materials of known hardness can be a simple way to approximate the position of a mineral on the scale.

Is 7 on the Mohs scale hard?

10Diamond9Corundum (rubies and sapphires)8Topaz7Quartz [Example: It scratches window glass]