What is apatite?
Apatites are a group of phosphate crystals that contain high concentrations of negative hydroxide (OH−), fluoride (F−), or chloride (Cl−) ions within their structure. These minerals and their synthetic analogues represent a major class of ionic compounds and the most common crystalline form of calcium phosphate, which is of interest to many industries and disciplines. Apatites are found in sedimentary rocks, metamorphic rocks, igneous rocks and volcanic rocks and can be formed during sedimentation processes, volcanic processes, metamorphic processes and hydrothermal fissures, as well as biological systems.
The apatite mineral was first identified by the German geologist Abraham Gottlob Werner. He named this mineral from the Greek word apatao meaning deception. The reason for this naming was that apatite was confused with number of minerals.
One of the most popular apatites is hydroxyapatite, which is the main component of toothe enamel and bone minerals.
Another apatite is fluorapatite, which has a very high resistance to acid. In the 20th century, scientists discovered that fluoride could prevent tooth decay. This was discovered during a study of drinking water in areas where water contains higher fluorine. In these areas, people have a lower percentage of tooth decay. Therefore, fluoride ions are used in toothpaste, including sodium monofluorophosphate.
Applications of apatite
Since this substance is a rich source of phosphorus, one of its primary applications is in production of fertilizer. In addition to fertilizer production, it is used to produce animal feed supplements as well as phosphoric acid, phosphorus and phosphate compounds required in chemical industries.
The phosphate component in phosphate rock is a form of apatite mineral and according to the origin of phosphate rock and its geological history, these apatites can have a wide variety of crystalline diversity and physical and chemical properties.
According to global estimates, in 2019, China was the largest producer of phosphate ore in the world with 110 million tons. After China, the Morocco and the Western Sahara are next with 36 million tons and the United States with 23 million tons. In the same year, among the Arab countries after Morocco, Jordan was the largest producer of phosphate ore in the Middle East with 8 million tons, Saudi Arabia 6.2 million, Egypt 5 million, Tunisia 3 million and Syria 2 million tons.
Another application of this ore is in the production of phosphoric acid. Phosphoric acid is produced by dissolving apatites in sulfuric acid. This acid has many applications, including in the food industry.
In the process of producing phosphoric acid, another substance called hydrogen fluoride is produced as a by-product of fluorapatite. This by-product can be used as a source of hydrofluoric acid.
Transparent and colored types of apatite with green, blue, yellow and pink colors can be used as gemstone or ornamental stones. Sometimes, in order to increase the color quality of these stones, they are subjected to thermal processes.
Apatites are also used to host nuclear waste.