Mineral necessarily constant for all sides, which is a function of its structure; crystallographic weakness renders some directions softer than others. An example of this property exists in kyanite, which has a Mohs hardness of 5½ parallel to [001] but 7 parallel to [100]. The most common scale of measurement is the ordinal Mohs hardness scale. Defined by ten indicators, a mineral with a higher index scratches those below it. The scale ranges from talc, a phyllosilicate, to diamond, a carbon polymorph that is the hardest natural material. The scale is provided below: Lustre indicates how light reflects from the mineral's
Samuelsonite Samuelsonite Samuelsonite is a complex mineral that is found near North Groton, Grafton County, New Hampshire, US. Additionally, it is most commonly found as a secondary mineral in granite pegmatite. Samuelsonite is named after Peter B. Samuelson, a prospector from Rumney, New Hampshire. The mineral has a pale yellow color and has a hardness of 5 on Mohs scale. The crystal is generally yellow, flat, and with straited crystals and blue trolleites. Samuelsonite is monolinic. There are three vectors of unequal length in this crystal system. The three vectors form a rectangular prism with a parallelogram at the base. Therefore,