What is one way to tell which of 2 minerals is harder?

Answer 1

The hardness of a material is often confused with its inter-molecular bond strength. The hardness of steel is lower than that of diamond, however, diamond can be shattered by an impact that would most likely only dent steel of the same thickness. Why is this? It's because of how the bonds are organized. Diamond is a very complicated substance, and can be most easily compared with an ionic bonded substance, such as table salt, or sodium chloride (NaCl). Because of the organization and bond-types of the individual elements, sodium chloride is NOT made from separate molecules, but rather one extremely large collection of sodium atoms and chlorine atoms that are all bonded together (similar to chicken-wire) Because the ratio of atoms of sodium to atoms of chlorine is 1:1, it is defined that one atom of sodium and one atom of chlorine makes table salt, though it would still be considered one unit of table salt if there were a thousand of each, all bonded together. While this increases the strength of the overall substance, it makes it extremely brittle. So basically, the atoms are either in the exact positions that their shape is made up of (for instance, a cubic crystal would have a cubic organization of atoms) or they are separated from the rest of the substance, meaning that if one pushed them even slightly out of the normal organization, it breaks.

The easiest way to determine the hardness of a mineral would be to take an object of a material that you know the hardness to, and see if it can scratch the surface of hte mineral. It is most efficient if you start with the softest you know of, and move up the scale to see PRECISELY where your said mineral lies.

Now if you're talking about hardness as a matter of how much IMPACT something can take before shattering, that's a bit more difficult, and honestly, I couldn't give you much of a straight answer. I'd say try testing several different substances with it (going from those that crush easily, to something like a metal hammer, and seeing how easily, if at all, it could crush the substance)

Answer 2

To my understanding, there is a rock/mineral hardness scale from 1-10. 1 being chalk and 10 being a diamond. To figure out if a rock/mineral is soft, they do a scratch test and which ever one looses bits and pieces is the softer of the two and visa versa. You repeat this step to see where it falls in the hardness scale.

Answer 3

Scratch those two materials and whichever one scratches the other one is the one that is harder.