Fluorite is also called fluorite, fluorite powder and fluorite powder. It is a mineral with equiaxed crystal system, and its main component is calcium fluoride (CaF2). There are many impurities, and Ca is often replaced by rare earth elements such as Y and Ce. In addition, it also contains a small amount of Fe2O3, SiO2 and trace amounts of Cl, O3 and He. Fluorite in nature often presents bright colors, and some can emit fluorescence. Mohs hardness 4, lower than steel, easy to scratch, brittle, sweet, astringent and non-toxic. Melting point: 1270- 1350℃. Density: 3. 18g/cm? Refractive index: 1.434. It can be used to prepare hydrogen fluoride: CaF2+H2SO4 = CaSO4+ 2HF↑, which is one of the materials used to make optical glass for lenses.
The night pearl is a rare gem, which was called "following the pearl", "hanging the pearl", "hanging the ridge" and "bright moon pearl" in ancient times. Usually, the luminous pearl refers to fluorescent stone and luminous stone. It is formed by some luminous substances in the earth after tens of millions of years, from the initial volcanic magma eruption to the later geological movement, gathered in the ore. After processing, the stones containing these luminous rare elements are what people call the night pearl, which is often yellow-green, light blue, orange and other colors. Fluorescent stone under white fluorescent lamp will emit beautiful fluorescence, which is obviously weak in the day and strong at night. In addition, some handicrafts also use the characteristics of fluorite to make some ornaments called "Night Pearl".
Due to the different activators in active crystalline phosphors, active crystalline phosphors, namely "luminous pearls", can be divided into two categories:
Rare earth luminous pearl
1, permanently luminous night pearl: it does not need any external energy excitation, but it can emit light by itself by containing an activator, such as radioactive isotope14c.3h.147pm.226ra.232nd. ..
2. Long-lasting luminous luminous luminous pearl: The activator in the phosphor is not radioactive and must be excited by external sunlight, ultraviolet rays and other light sources to emit light. At present, there are more than 100 kinds of commonly used phosphors, all of which are compounds of divalent metal (calcium, strontium, barium, cadmium, magnesium and zinc) sulfides, selenides, tellurides, silicates, aluminates, tungstates, phosphates and halophosphates, except alkali metal halides.
Among them, silicate and aluminate rare earth luminous luminous pearls are widely used because they use new rare earth luminous materials as the main raw materials, which are non-toxic, harmless and radiation-free, environmentally friendly and healthy, such as artificial strontium borate luminous elastic balls (dragon balls). Natural luminous pearls are extremely rare. We can not only use the scientific detection instruments of precious stones, but also identify their authenticity according to their many characteristics.