Bauxite is a rock that is mainly composed of aluminum minerals such as bohemite, gibbsite and diaspore, it does not have a specific chemical composition. Its origin is due to weathering and leaching of aluminum-rich rocks and it is the only major source of aluminum.
Characteristics and physical properties
| Bauxite | Characteristics and physical properties |
| Chemical composition | It does not have a defined composition, it is considered a mixture of hydrated aluminum oxides, aluminum hydroxides, clay minerals and insoluble minerals. |
| Hardness | 1 to 3 |
| Density or specific weight | 2 to 2.55 g/cm3. |
| Brightness | matte to earthy |
| Color | White, grey, yellow, orange, pink, red or brown by iron. |
| Stripe | Usually white. |
| Fracture or cleavage | None, does not present. |
| crystalline system | None |
| Origin and geological environment | In tropical climates, product of weathering and leaching of aluminum-rich rocks. |
| associated rocks | Sedimentary rocks. |
| Associated minerals | Gibbsite, diaspora, bohemite. |
| Applications | Main aluminum ore, synthetic bauxite is used as an abrasive and proppant. |
The bauxite it is a rock that contains mainly aluminum ores, it is not a mineral as most of us thought because we found it in the mineral list, but it is kept in the minerals because it contains the name of a commercial valuable substance.
This rock is the most important source of aluminum, this metal is very valuable in the commercial industry.
The bauxite It can contain several aluminum minerals such as boehmite, diaspore and gibbsite, it occurs in granular, earthy masses or with a pisolitic structure.
Its color is white, gray, red, pink, orange, yellow and the brown color is due to the presence of iron.
Regarding some physical properties, it is characterized by having a low density between 2 to 2.55 g/cm3, the Mohs hardness is from 1 to 3, so it is a soft or soft material, its shine is mainly earthy and it does not present a crystalline system.
Because it does not have a defined composition, it is composed of a mixture of aluminum hydroxides, hydrated aluminum oxides, clay minerals, insoluble materials (quartz, hematite, siderite, magnetite, goethite)
Origin, formation and geological environment.
The bauxite, its origin is due to the leaching of silica latería soils or other soluble materials in tropical or subtropical climates.
Its formation occurs in tropical climates as a product of the weathering and leaching of rocks that contain aluminum silicates where the minerals are removed from the superficial layers, these silicates are washed and the hydrated aluminum oxides remain in place.
In addition, the bauxite deposits are extensive with little depth where they present nodular, earthy habits or a pisolitic structure. These deposits are usually soft and can be easily crushed.
Its formation can also be the product of the weathering of clayey calcareous rocks, which can be marly limestone or calcareous claystones, later these derivatives precipitate colloidally and the transport and deposit conditions form large sedimentary formations of bauxite.
How to identify bauxite?
As previously mentioned the bauxite it is a type of rock that contains aluminum minerals such as gibbsite, diaspore and boehmite and therefore does not have a specific composition.
It presents a pisolite structure that is a distinctive characteristic of the bauxite, nodular and earthy habits, and it is considered a soft mineral due to its hardness of 1 to 3 in reference to the Mohs scale.
Its color is white to gray, reddish brown, pink, orange and yellow, it has a generally earthy shine and it has a low specific gravity that is between 2.0 and 2.5, those mentioned properties are useful to recognize the bauxite.
Applications
The bauxite It is used for the production of aluminum, because it is the only important source of aluminum, it is an important metal in the world due to its low density and great resistance and it is used in:
- Veneers
- Aluminum tubes and castings
- Cars and in railway wagons due to their low weight
- Cookware
- household items
- Paints, aluminum foil and salts.
- The bauxite it also has great importance as an abrasive, therefore Al2O3 is made.
- Manufacture of aluminous refractory products.
- Synthetic alumina is used to make heat resistant porcelain. Example: spark plugs for internal combustion engines.
- Synthesized bauxites are also used as proppant for oil fields.