Surprisingly, there are more precious metals than gold - rubidium and cesium

Rare metal cesium and rubidium mineral resources have rare and precious reserves worldwide. Speaking of rarity, firstly, they are the alkali metals with the lowest content in the earth's crust, and secondly, they are sparsely distributed or difficult to extract from ores; Speaking of preciousness, it is generally believed that precious metals such as gold, silver, and platinum group metals are expensive, but in fact, cesium and rubidium are even more expensive than gold. The United States and China are the world's top and second largest producers and consumers of cesium and rubidium resources. Due to the scarcity, high cost, and irreplaceable position of cesium and rubidium mineral resources in the high-tech industry chain, their supply security has increasingly become one of the most important strategic layouts for major economies such as the United States and the West.

Cesium [s è] from gold, color sound. A rare alkali metal element Caesium or Cesium. Old translation 鏭. Element symbol Cs. Atomic number 55. Located in Group IA of the 6th cycle of the chemical periodic table. Famous German physicist Gustav Robert Kirchhoff (1824-1887) developed a spectrometer during his time at Heidelberg University. He collaborated with one of the groundbreaking chemists in the history of chemistry, Robert Wilhelm Bunsen (1811-1899), to establish the spectrochemical analysis method (burning various elements on a Bunsen lamp to emit some bright line spectra with a certain wavelength, which can sensitively determine the existence of certain elements), known as the "magical eye of chemists". They used this method to successively discover cesium and rubidium elements. In 1860, Robert Wilhelm Bunsen and Gustav Robert Kirchhoff discovered the "sky blue" spectral line while conducting spectroscopic experiments on extracts from Durkheim mineral water, which led to the discovery of cesium element. They named it "Coesius" in Latin, meaning sky blue. In fact, as early as 1846, Professor Pratler of Metallurgy at Freiberg University of Technology in Germany analyzed lepidolite (i.e. lithium mica) ore and discovered the presence of cesium sulfate. However, he mistakenly identified cesium sulfate as a mixture of sodium sulfate and potassium sulfate. Unfortunately, cesium slipped out of his hands. Cesium metal was not obtained until 1882 by the German chemist Seidberg through electrolysis of a mixture of cesium cyanide and barium cyanide. Cesium is mainly found in minerals in nature, and a small amount of cesium chloride is also found in carnallite.

Rubidium [r ú] comes from gold, like sound. A rare alkali metal element Rubidium. Element symbol Rb. Atomic number 37. Located in Group IA of the 5th cycle of the chemical periodic table. Rubidium was first discovered in lithium mica. Lithium mica was found in the 1860s. Its properties are very strange. When thrown into the burning coal, it will vomit foam, and then harden like glass. Analysis shows that it contains lithium and potassium, but it also harbors a secret. In 1861, Bunsen and Kirchhoff dissolved this mineral in acid at Heidelberg University, and then precipitated potassium. They then tested the residue, which showed two strong ruby red atomic spectral lines that had never been seen before, confirming that they contained a new element. They named it Rubidium after the Latin word "Ruidus" (deep red). Pure rubidium metal samples were finally produced in 1928. Rubidium is a rare independent industrial mineral, often dispersed in lithium mica, iron lithium mica, cesium zeolite, salt deposits, and mineral water. After Bunsei and Kirchhoff discovered cesium and rubidium using their established spectroscopic analysis method, spectroscopic analysis was widely applied in the field of elemental analysis.
1. Characteristics and properties of cesium and rubidium
Cesium crystal is a cubic core lattice, with a pure golden yellow color, soft (Mohs hardness of 0.5), light, and ductile. The melting point is very low, only 28.4 ℃, the boiling point is 669.3 ℃, and the density is 1.8785g/cm3. Cesium is the element with the largest atomic radius (265.4pm). Excluding the radioactive element francium, cesium is the most reactive metal in nature, easily oxidized in air, and reacts violently with water and ice at -116 ℃. Has a sensitive photoelectric effect and is highly prone to ionization, releasing electrons. Cesium does not react with nitrogen, but can react with hydrogen at high temperatures to produce relatively stable hydrides. Cesium iodide reacts with bismuth triiodide to form insoluble bright red complex salts. Cesium compounds mainly include cesium carbonate, cesium formate, cesium bromide, cesium chloride, cesium fluoride, cesium iodide, cesium hydroxide, cesium nitrate, cesium oxide, cesium sulfate, cesium alum, etc.

The crystal structure of rubidium is a cubic core cell, a silver white waxy solid, with a metallic luster, a soft and light texture (Mohs hardness of 0.3), and ductility. Low melting point of 38.89 ℃, boiling point of 688 ℃, density of 1.53g/cm3. The atomic radius of rubidium is second only to cesium (247.5pm). Rubidium has properties similar to cesium, with extremely active chemical properties. It immediately loses its metallic luster in air, is violently oxidized by oxygen, and can cause spontaneous combustion. The reaction is very intense when in contact with water, and even explosions can occur when exposed to ice cubes below -100 ℃. Has a keen photoelectric effect.

2. The use of cesium and rubidium
Cesium has a wide range of applications. Cesium metal and cesium salts are irreplaceable in many industries. Cesium has many unique physical and chemical properties, such as extremely high conductivity, extremely low melting point, and strong absorption, making it widely used in different fields. From the discovery of cesium in 1860 to 1926, there was no substantial industrial application. Afterwards, cesium was used as an absorber for electron tubes, and later primarily for the production of photovoltaic cells and other photosensitive components. Until the late 1970s, most of the limited production value of cesium was used for research on thermal ion power conversion, magnetohydrodynamics, and ion engine propulsion. The application of cesium salts in the chemical industry, petrochemical industry, fine chemical industry, and biotechnology is constantly expanding. At present, cesium has become an irreplaceable resource for other metal elements and is known as the "industrial gold of the 21st century". In fact, its price is more than ten times more expensive than gold. At present, it is mainly used in fields such as national defense and military industry, aerospace, atomic clock, communication, energy, chemical industry, geological exploration, and medical care.

(1) Defense industry, aerospace industry
Cesium element is one of the important materials for manufacturing atomic clocks, which are highly accurate time meters with an error of no more than one second every three million years. They are mainly used in global navigation systems. It can also produce ion engine thrusters, night vision imaging devices, alarms, phototubes, photovoltaic cells, radio tubes, infrared signal lights, and various optical and detection instruments, as well as manufacture nuclear weapons and missiles.
(2) Geophysical, geochemical exploration, and oil and gas exploration fields
Cesium element can be used to detect and study underground minerals and geological structures, serving as a radioactive tracer to measure the properties of underground rocks and soils. Used for oil and gas extraction, its compounds cesium formate and cesium carbonate are high-density drilling fluids that can improve the stability and efficiency of drilling fluids, prevent wellbore collapse and gas leakage. Used for industrial radioactivity measurement, radiation detectors, television camera tubes, photomultiplier tubes, etc.
(3) Military civilian communication field
Cesium can be used to manufacture fiber optic cables, photodetectors, lasers, and other equipment to improve the speed and quality of signal transmission. Cesium is also a key material for 5G communication technology, used in 5G, ion cloud communication, fiber optic communication, and more.
(4) Energy sector
Used for making magnetic fluid power generation materials, thermal ion conversion power generation, etc.
(5) Used for industrial catalysts and glass and ceramic production
Cesium element can be used as a catalyst to accelerate the rate of certain chemical reactions, such as ammonia, sulfuric acid, hydrogenation, oxidation, polymerization, and other synthesis reactions. Cesium compounds are used to make special glass and ceramics, which can reduce the conductivity of glass, increase its stability, and extend its service life. Cesium can be used to produce high-performance cesium potassium fire-resistant glass and other materials.
(6) Used in the medical industry
Cesium element can be used as a radiation source, and the radioactive properties of cesium-137 isotope are an effective tool for treating cancer and epilepsy. Cesium salts can also be used to prepare sleeping pills, sedatives, and shock absorbers, and cesium can also be used as a material for medical imaging equipment. Cesium-137 can be used for radiation breeding, food radiation preservation, etc.

Rubidium and cesium have similar physical properties and atomic radii, so their applications are similar and they can be used interchangeably in many applications. Rubidium also has a wide range of applications in new materials, new pharmaceuticals, catalysts, environmental protection, national defense and military industry, aerospace, information industry, and civilian life.
(1) Energy sector
It can be used for the production of solar cells, photovoltaic power generation systems, optoelectronic semiconductor devices, rubidium magnetohydrodynamic power generation, and thermal ion conversion power generation. Rubidium has the same conductivity as sulfuric acid at a temperature of 20 degrees Celsius, and because of this characteristic, rubidium can be used for the manufacture of ultra-thin cells.
(2) Information technology and electronics field
Rubidium can be used as a high-performance material in devices such as optical displays, fiber optic communications, and lasers, improving the speed and accuracy of information transmission and processing. Rubidium can be used to manufacture electronic devices and semiconductor materials, as well as reinforcing agents in a few metal alloys. Rubidium also has important applications in fields such as laser technology, fiber optic communication, and satellite navigation systems.
(3) In terms of scientific research
Geologists use the radioactivity of rubidium-87 to determine the age of rocks or other objects. Rubidium is widely used in quantitative chemical analysis and atomic absorption spectroscopy to determine the content of other metal elements in samples. Rubidium plays an important role in nuclear and atomic physics research.
(4) In the medical field
Rubidium can be used for radiation therapy and nuclear medicine diagnosis of diseases, tracking the function and metabolism of human organs and tissues through nuclear labeling technology, playing an important role in early diagnosis and treatment of diseases. It has a very positive effect in treating depression, cancer, and Alzheimer's disease. Rubidium iodide is also an important medicinal herb for treating conditions such as hyperthyroidism, epilepsy, and syphilis. It is also an anti shock drug and an ingredient in eye drops after arsenic poisoning. Rubidium chloride can be used as a drug for anti manic and mood stabilizers.
(5) Used for the production of glass, ceramics, and fireworks
Rubidium salt can be used in the production of glass, ceramics, and fireworks, as a raw material for making purple, and can also be used to make special glass.
3. Famous cesium and rubidium deposits in China
China has abundant rubidium and cesium resources, with reserves ranking among the top in the world and a complete range of types, distributed throughout the country. The rubidium and cesium resources in China mainly exist in lithium mica and salt lake brine. The cesium and rubidium resources in China are mainly distributed in the Altai region of Xinjiang (48%) and Yichun, Jiangxi (25%), followed by Hunan (10%), Guangdong (9%), Qinghai (3%), Sichuan (3%), and Hubei (2%). Among them, the early developed Keketuohai mining area in Xinjiang has cesium zeolite concentrate containing about 18% -25% cesium oxide (Cs2O), and lithium mica containing 9% rubidium oxide (Rb2O), making it an important producer of rubidium and cesium in China. The total amount of hard rock cesium resources discovered in major mining areas in China is 61800 tons, but the vast majority are difficult to process cesium resources associated with lithium mica, which do not have independent development and utilization value. Generally, only cesium and rubidium associated mineral resources are extracted again from the tailings after lithium extraction from lithium mica.
There are currently no independently mined rubidium deposits in China, mainly existing in the form of associated minerals. According to the occurrence state of rubidium in China, rubidium can be divided into three types: lithium mica type rubidium mineral resources, feldspar type rubidium mineral resources, and cesium zeolite type rubidium mineral resources. Lithium mica type rubidium ore is widely distributed in Jiangxi, Hunan, and Henan provinces; Feldspar type rubidium deposits are mainly distributed in Xinjiang and Shanxi; Cesium zeolite type rubidium ore is mainly distributed in Xinjiang, Sichuan, Yunnan, Jiangxi, Hunan and other places.
In recent years, guided by the overall goal of protecting and rational utilization of mineral resources in China at the beginning of the 21st century, a new round of breakthrough strategic actions for mineral exploration has been launched to ensure the safety of strategic mineral resources. Various geological departments have increased their efforts in geological survey, exploration, and research, and have made a series of breakthrough progress. A batch of large and super large rubidium deposits have been discovered in the cesium rubidium mineral resources, breaking the monopoly of the United States and making China the country with the largest reserves of rubidium resources in the world.
① South section of Mount Wuyi metallogenic belt in Guangdong
② Xiangyuan Mine, Dao County, Hunan Province
③ Changchengling Mining Area, Yizhang County, Xiangnan
④ Guobaoshan Rubidium Deposit in Gansu Province