How is the hardness of a mineral determined and what methods are used to measure it accurately?

The hardness of a mineral is determined by its resistance to scratching. The most commonly used method to measure hardness is the Mohs scale, which ranks minerals from 1 (softest) to 10 (hardest) based on their ability to scratch each other. Another method is the Vickers hardness test, which measures the resistance of a mineral to indentation using a diamond indenter.