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
Mineral industry of Azerbaijan produced steel products from steel scrap. In 2005, production increased for practically all mineral commodities. Crude petroleum production increased by more than 43% compared with that of 2004. The country was developing its steel industry, although it is still on a small scale. Fuels accounted for 76% of the value of exports in 2005. The country’s major export was crude petroleum, almost all of which was sold on world markets rather than supplied to other CIS countries. Other mineral exports included petroleum refinery products and alumina. The country imported a variety of mineral commodities, including natural gas. Azerbaijan’s major mineral