The Mohs scale of mineral hardness was created in 1812 by German geologist Friedrick Mohs. It allows you to attach a measurable number to the hardness of different materials. It is a scale of 1-10, with 10 (diamond) being the hardest. Existing mortar usually falls between 2-8 on the scale. This analysis of the failing mortar ensures that we use only compatible mortar during the tuckpointing process. Using this experiment helps decide which mortars to use when replacing the deteriorated mortar and crumbling brick.