The Mohs scale was introduced by a German Geologist Fredrick Mohs in 1812. The method was basically the vulnerability of a mineral to scratch another and the effects.
To do this at home. You need to have a speciman that you know the hardness of. Thats going to be crucial. Here are a few hardness things you may have at home.
Your fingernail is about a 2.5
A penny is a 3
A steel nail is 5.5
A piece of glass is about a 5.5 to 6.5
A piece of quartz is a 7
A steel file is 6.5 to 7.5
A sapphire file is a 9 (I don't know how many of us would have this.)
If you start with the lowest know hardness. Find a clear spot on the stone to try and scratch it.
If it makes a mark than it is softer than your known substance.
For example: If I have a penny. Which I know has a hardness of three.
If I scratch my unknown sample and it does not leave a mark....then i can determine my unkown is harder than my penny. (above 3)
If I take a piece of quartz, which I know is a 7.
If I scratch my unknown and it does leave a mark....then i can surmise that the quartz is harder and the approximate hardness would be closer to glass at a 5.5 to 6.5
Petoskeys and other fossils are about a 3 on the hardness scale.
Unakite is 6 to 7
Puddingstones are kind of a mess, being a conglomerate, there can be multiple stones within the quartz matrix with different hardness's.
I have found this be be a great help in my search in learning what exactly i am picking up rockhounding.
This scale is put out by 911metalurgist.com. For more information please use this link.
https://www.911metallurgist.com/blog/mohs-hardness-test-kit
