The caliche is a rock that is formed by the cementation of particles found in the layers of the soil, for this reason, it is usually similar to a layer in the soil, but very compact.
Visually it is very similar to conglomerate, breccia and sandstone, but it must be remembered that this rock has formed in the same place because cement, which is generally calcium carbonate, has attached to the particles in the soil.
Properties and characteristics
This rock is usually a fairly hard, dense, resistant and heavy material, especially when the spaces between the particles are completely filled with cementing material, however, it can be a weak rock if the particles are not well cemented.
Geological environment
This rock is generated very easily or is common in arid or semi-arid areas, because it is necessary, a low percentage of water in the soil and poor drainage, in addition, there is no abundant vegetation.
Texture and structure
One of the characteristics of the caliche is that in terms of its structure and texture it has an appearance similar to conglomerate, breccia, coquina and also sandstone, this occurs depending on the type and size of particles that have been cemented.
Cementing material
The cement that joins the particles that make up the caliche is generally calcium carbonate, but as is known, this mineral is almost always accompanied by magnesium, gypsum, silica, and iron oxides, so it is concluded that the cementing material is a mixture of those minerals.
Outcrop
In outcrops this rock appears as a layer similar to a layer of soil, but more competent, that is to say that the particles are well cemented.
It is sometimes covered by uncemented surface material and plant roots generally do not penetrate the layer of developed caliches.
Color
Because it is related to carbonates, iron oxides, magnesium and gypsum, it usually occurs in a range of colors such as white, gray or reddish brown.
It is clear that, if it is enriched in iron oxides, it would have a reddish color.
Origin of the name caliche
The word Caliche It comes from the Latin Calx, which means lime, but the origin of this word has more history. Caliche It is also a word of Spanish origin, which they used to refer to some material that has suffered damage on its surface.
This rock formation can also be called by other names:
- Hardpan. This term is more used in gardening.
- Calcrete or Duricrust. It is known by this name in English-speaking countries.
- kankar. This is how they call the Caliche in India.
How is caliche formed?
The ways in which this surface is formed are diverse. But they all agree on the lack of water or its evaporation. Some of these processes will be described below.
Main process
There is an active chemical that will always be present in the formation of the Caliche, than calcium carbonate. This component seeps down from the soil surface.
Calcium carbonate precipitates in the form of small grains on the soil particles. This process will occur until all the particles, both soil and calcium, are united, forming nodules. As the process continues, a superficial and internal layer or crust will form.
Normally the outer layer is thicker. It can measure more than a meter thick and its lateral length can be kilometers. But the size decreases as it goes down into the ground.
As this process continues, a dense, impermeable layer of caliche that will be able to resist filtrations of abundant waters. It can also resist erosion by the effect of the wind.
Second process
The caliche It can also be formed by the intervention of water. This flows upward through the ground as the water evaporates. The chemical materials present there precipitate and, over time, cement the soil or sediments.
Third process
We have the Caliche formed by vegetation. Plants absorb water from the soil to feed themselves. The more amounts of plants do this process, they remove more amounts of water leaving the soil full of concentrated mineral materials. Over time, it forms caliche.
How to identify Caliche?
This surface has predominantly white, gray, brown and some reddish tones. The Caliche It is usually a very heavy, dense, hard and very firm rock thanks to the cement that originates in its formation process. This fills its empty spaces between the soil and the rock.
A caliche well developed is generally noted for being compact on the surface. When trying to remove it, loose soil is found underneath. Normally, if there is existence of plants, their roots cannot penetrate it. Sometimes it is usually compared with breccia, coquina or sandstone if the characteristics of the Caliche they are adequate.
Extraction process
The caliche It is extracted with normal loading machinery. Usually a section is chosen. In this, marks of 25 meters by 25 meters are made on the surface to then break the crust and extract in the form of blocks.
Then they are coupled in piles to carry out a process called Leaching. This process seeks to dissolve soluble mineral materials and leave the stone cleaner. This solution is collected through drainage systems, ending up in settling tanks.
After the previous process, the destination of the result is decided by requirements. Iodine can be extracted from the solution obtained. And from the rock, through a different process, a base for cement can be produced.
Caliche Uses
Caliche as a material can be used for different works such as the following:
- Barrier for water leaks.
- Barrier against erosion caused by wind.
- The caliche inside it can house gold, some precious stones and valuable minerals.
- Thanks to its porosity Caliche it can serve as a deposit of valuable secondary minerals such as uranium and vanadium. You can also deposit gems such as turquoise or malachite.
- The Caliche it is sometimes used to calculate the relative age of the soil and strategic markers.
- Analysis of this surface provides researchers with weather, tectonic, sedimentary, erosive, and hydrological stability information.
- It is also used ground, as filler, aggregate or raw material to make cement.
Caliche problems
Here are some negative implications of the Caliches :
- The sediments of the caliche They can become very dense, being a problem when building.
- These sediments, if found on terraces, can influence the topography of the place.
- These layers of Caliche in aquifers they cause stratified flow of water in the subsoil.
- In agriculture, the Caliche its a big problem. As an example of this, it is known that it interferes with the proper drainage of soils and impairs the formation of roots in plants. In its composition it may have some soluble minerals that are toxic or not very beneficial for the crops.
