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Minerals and mineralogy

Welcome to the homepage of minerals and mineralogy. If you want to learn something about this beautiful world or if you want know your jewels better you should look at this website.

Mineralogy is the science which analyses minerals. Here we have to define what minerals are. A mineral is a solid or liquid material with certain chemical and physical properties which is in the earth. In comparison to minerals rocks are very different. Since thousands of years people are fascinate of minerals. There are about 3000 known minerals, but only few of them are fascinating got people. Their look is the reason why they pleases to people. Very beautiful minerals are often transparent and they have got a nice color or form. The popularity of a minerals decides if it is a precious stone or not.

The formation: There are three developing processes: the macmatic developing process, the sedimentary developing process and the metamorphically developing process. The magma is known as the material which comes out of volcanos and is called lava. It is a liquid in the earth with a temperature of 1300 degrees. When the magma comes out of the earth to the surface it becomes colder and it crystallizes. The first minerals are formed which are deep in the earth. On the way to the earth surface the magma becomes high liquid and it crystallizes. One of the last phases is the hydrothermal phase. In this phase some gases leave the magma und flow to the top. Often these gases forms rooms in the rocks. These rooms are later filled with magma. In this phase quartz (rock crystal, amethyst) originate. This is the reason why quartz is often in closed rooms of rock which are called geodes. Generelly quartz grows in cracks of rock. In the sedimentary developing process minerals originate because of many enviromental factors. High temperatures can cause new chemical connections. Strong frost can have an explosive effect. There also also acid and other substances, because fo the rain. Water and the oxygen in the air can also react with minerals and so new minerals are formed. In the metamorphically developing process it is so that magma flows again throught the rocks where minerals already exist. Here the magma alters these minerals. There are special developing processes for organic minerals, too.

Chemical and physical properties: Every mineral has got certain chemical and physical properties. Every mineral has got a structure. The easiest structure is an element, but most of the minerals are molecules or ions and so they have got a chemical formula. The chemical formulas are described in the chapters about the minerals. Here we will look at the 9 mineral classes in which the minerals are arranged.
  1. Elements (diamond, gold, silver)
  2. Sulfides, selenides, tellurides, arsenides, antimonides and bismutides (pyrite)
  3. Halides (fluorite, rock salt)
  4. Oxides and hydroxides (corundum, quartz)
  5. Nitrates, carbonates and borates (calcite, malachite)
  6. Sulfates, chromates, molybdates and tungstenates (alabaster)
  7. Phosphates, arsenates and vanadates (turkis)
  8. Silicates (feldspar, topaz)
  9. Organic connections (amber)
Most of the minerals form crystals. Crystals are a symmetric order of atoms, molecules or ions. It is called crystal lattice. An arbitrary order is called amorph. There are 7 different crystal systems for minerals (cubical, monoclinical, triclinical, hexagonal, trigonal, tetragonal, rhombical). Rock salt for example crystallizes in the cubical system. Because rock salt (NaCl) is also common salt (NaCl), we can see little cubes in the common salt. It is easier to see in bigger pieces. So minerals which crystallize in the cubical system have got the form of a cube. Quartz and corundum (ruby, sapphire) crystallize in the trigonal system. When the material does not comes regular during the formation of a mineral then the crystal would not be perfect. Other factors have also an influence of a wrong form of a crystal. A too small room or other materials can change the crystal form, too. Nearly never we can find perfect crystals. The relation between the perimeter and the height is not always the same. When the room is too small then often one crystal grows into another crystal. Another property of minerals is their density. The density is the mass per volume. It is gram per cubic centimetre (g/cm3). Water for eample has got a density of 1 g/cm3. Most of the minerals have got a higher density than water and so they sink in water. The hardness is another property. The hardness is the possibility to break into a mineral. There is the Mohs' hardness scale. It is from1 to 10. A mineral with the hardness of 1 can be scratched with the finger nail. The diamond with a hardness of 10 cannot be even scratched with a knife. A mineral with a higher hardness can scratch a mineral with a lower hardness.

Mohs' hardness scale
1 talc2 gypsum3 calcite4 fluorite5 apatite
6 feldspar7 quartz8 topaz9 corundum10 diamond

Many minerals can be splited throught an impact with a hammer. A mineral can be splited well in one direction, but for example not in another. There are also minerals without a certain fissileness. They break casual. Here we can see the break. The color is the easiest property. There are colorless minerals like the rock crystal and the diamond. Other quartzs like the amethyst have got a color, because of admixtures. They are colored minerals. The third group are minerals which have got an own color, because of their chemical and physical properties. To see wheather a mineral is colored or has got an own color we can pass it over a surface and look at the abrasion. It is the line color. The gloss of a mineral is another property. There is diamond gloss, glass glos, fat gloss and metal gloss. The transparency is very important, too. Clear minerals have got a high transparency, but the transparency is caused by the chemical and physical properties of the mineral.

Mineral database (sorted by mineral classes)

Author and Webmaster: Lukas Czarnecki

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Last Update: 21.01.2006