There are a number of hardness scales used in modern science. The Moh's hardness scale measures the ability of one sample to scratch another. This is still often used to identify minerals especially by amateurs. Moh's suffers from some some inadequacies, for example one crystal face may be harder than another in a given sample. Metals such as potassium are more often rated on other scales, for example Rockwell or Brinell hardness tests which measure the ability of a diamond point to indent the sample. The Wikipedia page for Potassium gives the moh's hardness as 0.4 however.
Diatomite has a hardness of around 5.5 on the Mohs scale of hardness.
It's called the Ore
Azurite has a hardness of 3.5 to 4 on the Mohs hardness scale.
flint is a type of quartz, so it has a hardness of about 7 on the mohs scale of hardness
Dolomite has a hardness of 3.5-4 on the Mohs scale of hardness.
Diatomite has a hardness of around 5.5 on the Mohs scale of hardness.
It's called the Ore
The hardness of Limonite is 4 t0 5.5 on the mohs hardness scale.
Azurite has a hardness of 3.5 to 4 on the Mohs hardness scale.
flint is a type of quartz, so it has a hardness of about 7 on the mohs scale of hardness
Nickel has a hardness of 4 on the Mohs scale.
The hardness is 3-4 on Mohs scale.
Dolomite has a hardness of 3.5-4 on the Mohs scale of hardness.
The Mohs scale is used to determine the relative hardness of minerals.
This scale was proposed by the Austrian geologist Friderich Mohs.
Aluminum Oxide is roughly 8.5 - 9.0 on the hardness scale.
Granite is not assigned a number on the Mohs scale of hardness. The Mohs scale is a measurement of the relative hardness of minerals. Because granite is a rock composed of a variety of minerals, only the individual minerals which compose it have a Mohs hardness.