Countless treasures are hidden in the bowels of our planet. Most precious and semiprecious stones have a smooth surface with clear edges that give them certain outlines of symmetry. Since the 18th century, such bodies have been called crystals, although among the ancient Romans and Greeks this term was used in relation to rock crystal. In a literal translation, the word "crystallus" means "frozen." In those days it was believed that this was compacted ice. This myth was debunked by Robert Boyle, proving that rock crystal is heavier than water, and therefore cannot be frozen water.
What is a crystal
Crystals are solids with atoms arranged in a specific order, forming a three-dimensionally periodic spatial arrangement. Externally, such bodies have regular and symmetrical multiple faces.
The first who gave a broader concept to the word “crystal” was Kappeller. Although the understanding and the law of constancy of angles was established by Niels Stensen in 1669.
The modern concept is formed in the International Union of Crystallographers, and is interpreted as a body having a predominantly sharp diffraction form.
The concept of a crystal includes not only diamond and other minerals with a certain structure, but also sugar, even freezing water.
Classification
What are the crystals? In the modern world, all crystals are divided into 32 types and are grouped into 6 types. Also, such solids are divided into:
- natural, that is, extracted from the bowels of the earth;
- artificial, that is, created by human hands (the most striking example is Swarovski crystals).
Real and ideal crystals are also distinguished. The latter form has perfect symmetry, without defects. A real crystal must have some kind of defect, that is, irregularities and deformations are observed.
There is a classification that separates crystals at the level of atoms and groups of molecules. In this case, single crystals are isolated that have a multifaceted shape and do not consist of separate parts. Polycrystals are several single crystals fused together.
What are the crystals yet? Precious and non-precious, that is, classified by aesthetic and economic criteria.
Diamond
The most famous and expensive crystal in the world. Under normal conditions, this mineral can exist forever, but if it is placed in an inert gas or vacuum, it will turn into graphite.
Diamond mining at an industrial level is carried out on all continents. Although their origin and age could not be established. Even minerals of extraterrestrial origin are known that hit the earth, formed during shock metamorphism in the process of meteorite fall.
The vast majority of diamonds mined on our planet are yellow or brown. But there are also quite unique ones - green, mauve and blue, even black. The most famous are Porter Rhodes in blue and Dresden green. The most valuable are those that have a unique color, in particular ruby red, cherry, blue and gold.
In the natural environment, diamonds are found in all kinds of shapes: from round and oval to pentahedral.
One of the most expensive is considered a red diamond, of which there are only 50 in the world (with perfect purity). The most expensive 5.11 carats is called the Red Shield. The name is given in the form of a crystal; at the beginning of our century it was sold at auction for $ 8 million.
Aquamarine
What kind of crystals are very similar to ice? This is aquamarine. The mineral is a type of beryl, and its name translates as "sea water." In shape, the crystals resemble long-columned and hexagonal prisms with a strong glass luster. The mineral is very fragile and easy to crush.
In jewelry, aquamarine gained popularity only at the beginning of the 20th century, when the style of art deco came into fashion. Deposits of this mineral are on the whole planet; they are extracted from pegmatites, which are located in coarse-grained granites.
The largest mineral was found in 1910, its weight was 110.5 kilograms.
Amethyst
What types of crystals are still? Amethyst is classified as semi-precious or semi-precious stones, depending on the color. If the color is opaque, then this is an ornamental stone, respectively, transparent is appreciated by jewelers.
It happens purple, cherry, blue, red. A unique feature of this quartz is that the shade changes depending on the lighting. Some amethysts found in sedimentary rocks fade when exposed to sunlight.
Turquoise
What are the crystals? Everyone knows the name of this mineral - turquoise or a stone of happiness. It has been popular since ancient times.
In shape, the mineral is presented in the form of cryptocrystalline dense mass. The stone contains small inclusions of rounded shape. On a section veins of brown or black color are visible. The color of the mineral varies from sky blue to faded green.
Emerald
What crystals are in nature yet? Emerald - a precious mineral from the beryl group, refers to the first-order gems. Large (from 5 carats) and defect-free emeralds are more expensive than diamonds.
The color of the mineral varies from yellowish-green to grassy-greenish, the main condition is the presence of a green tint. Stones mined in South African countries have an admixture of iron oxide, so they have a bluish tint.
One of the most famous in the world is the Devonshire Emerald, its weight is 304 grams. And the most famous in Russia is the Kokovinsky emerald weighing a little over 400 grams. It was mined in the Urals in 1833.
Malachite
What are the other crystals in the world besides those listed? Malachite is a valuable ornamental mineral of green color. The forms of stone in nature are diverse. Rare specimens of the mineral have a pronounced crystalline form; in large quantities it is very rare in one place. In Russia, almost all mineral reserves have been exhausted. For a long time, malachite ore was used to produce copper.
Rhinestone
What color are the crystals? There are even colorless, with glass shine, and in this case we are talking about rock crystal. This is pure silica - a colorless variety of quartz. The shape of the mineral may be trapezoidal or prismatic.
This group includes several varieties: hairy, rauchtopaz, amethyst, citrine and morion.
The mineral is in demand not only among jewelers, but is also used in radio engineering. Large sizes of natural material are quite expensive. The main thing is not to confuse rhinestone with what is sold in stores. To obtain glass luster in the manufacture of "crystal" glassware, barium and lead oxide are added to the glass.
Crocoite
What forms of crystals are there? The most unique include crocoite. Outwardly, it resembles dried saffron petals. Belongs to red lead ore from the chromate class.
The mineral is assigned to collection materials, as it has a unique color, shape and is very rare, is a satellite of lead ores.
The rarest types of crystals
Musgrave. Discovered it about 50 years ago in Australia. To date, only 14 copies have been found. Its colors are diverse: from light yellow with green hues to violet-purple. One carat of green musgravite costs 6 thousand dollars.
Grandidierite. Very rare crystal with a blue or green tint. A unique feature of the stone is the ability to change color. To date, only 20 minerals have been cut in the world, respectively, and the price of such products is very high - $ 30, 000 / 1.8 million rubles. for 1 carat.
Tanzanite What are the crystals? A photo of this stone can be seen in the movie "Titanic", where it was presented in the form of a blue diamond. The value of the mineral in its color, which varies depending on the lighting, and secondly, to date, only one deposit has been found - in Africa, the reserves of which will run out after 20 years.
Taaffeit. A very rare crystal, the cost per carat is from 500 to 20, 000 dollars (30, 000 - 1.2 million rubles). Today, there are only 4 deposits: in Tanzania, Sri Lanka and in Russia (Eastern Siberia and Karelia). The color of the stone varies from pale pink to lavender.
