Mineralogy
"Hardness" is determined by comparison with other minerals. In the Mohs scale, a standard set of minerals are numbered in order of increasing hardness from 1 (talc) to 10 (diamond). A harder mineral will scratch a softer, so an unknown mineral can be placed in this scale by which minerals it scratches and which scratch it. A few minerals such as calcite and kyanite have a hardness that depends significantly on direction. Hardness can also be measured on an absolute scale using a sclerometer; compared to the absolute scale, the Mohs scale is nonlinear.
Grit (personality trait)
Salvatore Maddi (2006) defined "hardiness" as a combination of attitudes that provide the courage and motivation to do the hard, strategic work of turning stressful circumstances from potential disasters into growth opportunities. While grit is primarily a measure of an individual's ability to persist in obtaining a specific goal over an extended time period (Duckworth et al., 2007), hardiness refers to an individual's ability to persist through difficult circumstances and does not address the individual's long term persistence toward a specific goal. Maddi (2006) developed a theoretical model of hardiness as a tool for developing resilience.