Grenades are a large group of similar stones, which some classify as ornamental, others to the noble ones. Chemically, they belong to the silicates in the general formula M.3R2 (SiO4)3. If you are interested in the actual chemical structure of grenades, I encourage you to study the table, which also shows the color Grenades depending on their chemical composition and, of course, on contamination with other metals.
The color palette of pomegranates is, as you can see, very rich – almost full. The most common pomegranates are glossular, pirop i almandyn. The last one, called by everyone the noble grenade, beautiful violet to blood red, it is the most sought after and most willingly framed. The most beautiful specimens of almandine come from Brazil, Ceylon and Peru. In Poland, almandin was found in the Tatra Mountains and Lower Silesia, although ruby-red piropy and dark colored glossulary are much more common in Poland.
CHEMICAL COMPOSITION AND COLORS OF NAVY BLUE
|andradyt||That3Fe2(SiO4)3||green, yellow, brown, black|
colorless, asparagus green, yellow, pink, brown
|spessartyn||Mn3Al2(And04)3||Orange, brown-red, brown|
|almandyn||Fe3Al2(Si04)3||Violet, cherry, blood red, brown-red, almost black|
Pomegranates have been a popular gemstone for many centuries. We already know, that they have long been tried to imitate them, m.in. golden ruby – glass colored by the addition of finely divided gold. In Europe, pomegranates are the most numerous in Czechoslovakia. There were so many of them there, that they have become a symbolic national stone, framed in patriotic jewelry, and in the 17th century they became a symbol of Czech freedom. To this day, garnet jewelery is made in Czechoslovakia, though not as willingly worn as in earlier times.
Pomegranates have also been used in technology for a long time. Less hard than diamonds, and even corundum, are used for polishing very hard types of wood, bone products, skin, and even glass. Also today, special abrasive papers and fine-grained abrasive powders are made of grenades, some materials are polished. Nowadays, grenades have been used, among others, in. in a completely new field - as memory crystals. If garnet is synthesized under special crystallization conditions, one can obtain a crystal with magnetic properties dependent on the intensity of the incident light. Using this property, scientists developed a new way of recording information. The garnet single crystal is covered with a very thin polymer-plastic film, and then it is irradiated in a special apparatus by "writing” the desired information in the crystal. So much information can be stored on just one square centimeter of the crystal surface, how many hundred meters of tape are included – computer memory. Such grenades were called magnetic semiconductors, and the discovery of "crystals of memory” it is one of the steps of modern physics towards the future world described in science fiction.
The name pomegranate comes from the Latin word granatum = pomegranate - the fruit of the pomegranate tree. This is due to the similarity of the most common garnet crystals in a large cluster – mineral, for numerous pomegranate seeds – fruit. Also, the size of the pomegranate crystals is usually close to the size 2-3 millimeter pips. The exceptions are larger grenades. The largest in the Czechoslovak collection weighs only 11 carats, and the largest in the world, adorning the Order of the Golden Fleece kept at the Dresden Grunes Gewelbe (Zielona Komnata), weighs up to 48 carats, i.e.. not all 10 grams. Pomegranates have a density of approx. 4 g/cm, thus the largest known grenade in the world has a volume of approx 2,5 cm3. The bigger the grenade, the larger the memory store. For this very reason, to the efforts of chemists and physicists in the past, who wanted to synthesize jewelry grenades, the physicists joined, who need large single crystals of pomegranate for scientific and technical purposes.
We already know the oldest attempts. Our ancestors tried to obtain synthetic grenades by melting and cooling natural grenades or by fusing natural aluminosilicates with certain metals under high pressure..