Gunter's scale

Gunter's scale is a traditional tool used by geologists and mineralogists to compare the hardness of minerals. It ranks minerals on a scale from 1 to 10, with talc at 1 (softest) and diamond at 10 (hardest). The scale is based on the ability of a mineral to scratch or be scratched by others. For example, if a mineral can scratch something with a hardness of 5 but not something with a hardness of 6, it has a hardness around 5. This helps identify minerals quickly in the field, providing a practical way to estimate their hardness.