Bauxite is a sedimentary rock and is the main mineral resource, given the high concentration of aluminum hydroxide (30%-75%) it contains, from which is derived Aluminum.
Bauxite is usually dark orange-red color with whitish spots depending on the presence of other elements such as silica, iron oxides and titanium.
Using the Bayer process (learn more)
you get the aluminum hydroxide - alumina - then you get for electrolysis, with the Hall-Héroult process,
(learn more) the Aluminum metal.
World bauxite reserves were estimated in 2008 to be approximately 38,000,000 of thousands of tons, with concentration in Guinea, Australia, Viet Nam, Jamaica, Brazil, China.
The ore is extracted mainly from open-cast mines. In 2010 were extracted, worldwide, more than 160 million tons of bauxite.
Image from: Corso di Metallurgia dei Metalli non Ferrosi - Università di Trento