Hardness II

Moh´s scale of hardness is a way to decide what the hardness is of a particular mineral specimen you want to identify. The scale rates the hardness of ten minerals from talc (1) to diamond (10). We don´t usually have all the minerals on hand, so we substitute things like pennies and knives instead. If you can scratch the mineral with your fingernail, it´s a 1 or a 2. If you can scratch it with a penny, that means the mineral is about 3.5 or less. If you can scratch it with a knife blade or a nail, the hardness of the mineral should be about 5.5 or less. If the mineral can scratch glass (you can get them in hardness kits) the hardness is about 8 or higher.