Ruby
Chemical Formula
Al2O3
Chemical Class
Oxides
Properties
Ruby is a precious variety of Corundum, a high hardness mineral, losing only to Diamond. Ruby red color is caused by lower Cr (chrome) quantities, replacing Al (aluminum) in crystal structure.
Origin
Sabinópolis, MG
Curiosities
This corundum variety is used as gemstone, but it can also be blue, and this other variety is known as Sapphire.
Use
Due to its high hardness, it was widely used as abrasive and for polishing, and it has been modernly replaced by synthetic abrasives. It is also used in precision mechanisms, including special watches and engines. Mineral, gemological and collection species
Source: MM Gerdau - Museu das Minas e do Metal -