When we talk about biotite we are talking about a group of minerals within the phyllosilicates. In this group of minerals there are some such as phlogopite, annite and eastonite. Previously, the name biotite was used to denote only one mineral. This changed in 1998, when the International Association of Mineralogy decided to stop using the concept of biotite for a single mineral, but to apply it to the entire group of minerals.
In this article we are going to tell you what are the characteristics of the biotite group of minerals and what main uses it has.
Key features
One of the best known minerals within the biotite group is mica. Many of the minerals that make up this group are part of what is called mica. Among the main characteristics we have the following:
- The chemical formula of mica K (Mg, Fe) 3AlSi3O10 (OH, F) 2.
- These minerals usually appear attached to igneous or metamorphic rocks. We find a large amount of mica in granites, in addition to feldspars. To understand more about these rocks, you can consult our the characteristics of magma in volcanoes.
- The appearance of this mineral is very particular because it has forms of bonds and layers that are superimposed on each other.
- The predominant colors in biotite they are usually stopped with shades between green and black.
- Regarding its hardness, we find that on the Mohs scale it has a value between 2,5 and 3. Its density is 3,09.
It is quite easy to differentiate from other minerals if you look exactly at its dark color and its transformation through plates. In gardening, vermiculite is used, which is an altered species of biotite and it is possible that there are some errors in its identification.
How is biotite extracted?
The biotite extraction process is important for the subsequent classification of the mica obtained. Depending on the type of mica obtained, it can be used for specific purposes. The first step when extracting biotite is to separate the rock type from which it comes. Whether the rock is igneous, metamorphic, or granitic, the raw material must be obtained and the mica separated from the rest of the rock fragments. The yield of this mineral that is obtained from the rocks does not usually exceed 1-2%.
Once the small mica plates are obtained, they undergo an exfoliation treatment to cut them and undergo a new exfoliation process. After this procedure, the biotite is classified according to the size of the plates obtained, and this classification is linked to their transparency. Transparency is the variable used to determine the amount of foreign minerals it contains and the smoothness of its surface. Depending on these variables, it will be used for one purpose or another.
Uses and applications of biotite
This group of minerals has some very interesting properties, they are the ones that re-circulate them to one type of application or another. For example, it has a great thermal and electrical insulating power. Being able to withstand high temperatures, it has a great place in various industrial and domestic uses. One of the oldest applications of biotite and that surely we have ever seen, is that serves as part of salamander windows and other wood burning stoves. The old irons that were used for clothes also had a mica plate to be able to put them flat after use.
Some of the closest uses today is the part of the walls and windows of microwave ovens. In the field of electronics we can find biotite for manufacturing capacitors and transistors. Mica is a good insulator between plates. Boilers operating from high pressure also have biotite linings.
It is not only used for the construction of various plates but also happens through a grinding process. This grinding process can occur both with high humidity and dry. Once this procedure has passed, it can be combined with other products. In the case of moisture ground mica, it tends to be used closely linked to the paint and coating industry. This is because it has good slip, luster and shine properties. Some wallpapers used for walls and coverings are made comic wet groundThe same thing often happens with pearlescent pigments. These pigments are found in the paints of artistic products, so when studying the types of minerals, mica may be included.
On the other hand, we can also see that they are used in exterior paints, sealants and aluminum paints made with an endemic wet-ground base. If we go on to study the uses of the dry ground half, we can see that it is used with the hammer method for grinding and then passes through a sieve. This is how it is classified for the different uses. Dry ground mica is used in welding rods, making electrodes and in the manufacture of some types of cements. They are also used for the manufacture of tiles, roof finishing and concrete bricks.
Where are the biotite deposits?
The deposits of these minerals are mainly located in India. China is the main world producer of micas. At present, there are various types of marketing of both biotite and muscovite micas. Some of these productions are limited because there is poor performance in each blast. If little performance is obtained in each blast, production costs rise and, therefore, market prices increase.
The exploitation of biotite is considered today as a subsidiary exploitation of other main extractions such as granite in order to reduce production costs. Therefore, the main objective is granite extraction, and biotite is used as a byproduct. However, despite being a less profitable type of extraction, we cannot deny that mica remains one of the minerals with the highest performance in terms of thermal and electrical insulation.
I hope that with this information you can learn more about biotite.