Mineralogy
Mineralogy is the science that studies minerals.
A mineral is a substance naturally formed, usually inorganic , exceptionally organic. A given mineral is characterized by a chemical formula and crystal structure , that is to say, respectively, by the nature of the atoms that compose it and their arrangement in space. The mineralogy of the various approaches focused study of minerals on these theoretical bases.
Summary |
Several properties and methods used to characterize a mineral. To study a given mineral, the mineralogist operate, including:
- its crystal structure in the solid state (most often studied using X-ray diffraction);
- its chemical composition (often analyzed in the electron microprobe );
- its mechanical properties: density or density , hardness , cleavage , fracture, fracture, touch;
- its optical properties: color , trace , brightness , transparency , refractive index , interferometric analysis using X-ray;
- bonds between atoms, which may include: covalent, ionic, metallic, van der Waals ;
- its chemical properties: photoluminescence , reactivity with acids, staining in the flame;
- its phase (solid, liquid or gaseous);
- its solubility (in water and acids);
- its electrical and thermal properties.
List of minerals
The modern nomenclature is needed in the course of the nineteenth century, where the name stems from several reasons.
- a property characteristic (eg. magnetite )
- the name of the dominant chemical element (eg, the calcite )
- the name of a scientist (eg, the dolomite , dedicated to Deodat de Dolomieu )
- its color (eg, the azurite )
- a locality (eg the autunite was discovered near Autun , Saone-et-Loire ).
Today, there is an international organization to standardize the definition of mineral species: the International Mineralogical Association (IMA).
Exploration
Minerals are likely to be found in the following sources:
- the mines and quarries , which are choice areas for prospecting for minerals;
- the meteorites that fall to Earth by the thousands every day;
- laboratory and through the computer , researchers are combinations of theoretical mineral composite , which currently constitute the bulk of the discoveries.
The eight elements which alone constitute nearly 90% of the texture of the crust combine to form minerals. Silicate minerals and silica predominate in most common rocks, except limestone.
The hardness scale
The Mohs hardness scale was invented in 1812 by the mineralogist German Friedrich Mohs to measure the hardness of minerals. Number 1 being the least hard and the number 10 the hardest.
- 1. The talc
- 2. The gypsum
- 2.2. The nail
- 3. The calcite
- 4. The fluorite
- 5. The apatite
- 6. The orthoclase
- 7. The quartz
- 8. The Topaz
- 9. The corundum
- 10. The diamond
Related Sciences
The mineralogy is working with other sciences:
- The survey , which consists in seeking the field of mineral resources;
- the geochemistry , which studies the chemical constituents of Earth's crust;
- the petrography , who studies rocks (including minerals are constituents);
- the geology , which is to study the modes of deposit and the conditions of mineral formation;
- la minralogie descriptive , qui tudie le minral lui-mme ;
- the microminralogie , part of the descriptive mineralogy and minerals so that studies of millimeter size;
- the crystallography , which studies the structure of crystals;
- instrumental techniques of chemistry , to determine the chemical formula of a mineral;
- instrumental techniques of physics to study a number of properties of the ore, with:
- the X-ray diffraction to determine the disposition of the mineral constituent atoms, namely, , and the ,
- the polarized light microscopy to determine the exact nature of the ore,
- the goniometer to measure the angles between them are the various faces of the crystal and allow its identification,
- measuring electrical properties, magnetic, optical and fluorescent for further differentiation of minerals;
- the materials science , which studies structure and properties of compounds of technological interest which are often mineral phases;
- the computer , which produces programs that facilitate the study and development of new theoretical combinations of minerals.
Examples of minerals
Here is a list of common minerals:
- Sulphides
- Arsenopyrite : FeAsS
- Bornite ( rubescite ) Cu 5 FeS 4
- Chalcopyrite : CuFeS 2
- Chalcocite Cu 2 S
- Cinnabar : HgS
- Enargite Cu 3 AsS 4
- Galena : PbS
- Molybdenite : MoS 2
- Orpiment : As 2 S 3
- Pyrite : FeS 2
- Pyrrhotite : FeS
- Realgar : AsS
- Sphalerite : ZnS
- Stibnite : Sb 2 S 3
- Oxydes and hydroxides
Oxides of the form XY 2 O 4 are grouped under the name "spinel" which often (but not always!) X 2 + is a metal and a metal Y 3 + (hematite, pleonaste example). An example is the cons-ulvospinelle, TiFe 2 O 4: here the titanium oxidation number has 4 +, the iron 2 +.
- Halides
- Carbonates
- Sulfates
- Silicates
- Nesosilicates
- Andalusite : Al 2 SiO 5 (orthorhombic)
- Fayalite Fe 2 SiO 4
- Forsterite : Mg 2 SiO 4
- Kyanite Al 2 SiO 5 (triclinic)
- Sillimanite : Al 2 SiO 5 (orthorhombic)
- Inosilicates
- Phyllosilicates
- Chrysotile : Mg 3 Si 2 O 5 (OH) 4
- Kaolinite Al 2 Si 2 O 5 (OH) 4
- Muscovite : Kal 3 Si 3 O 10 (OH) 2
- Phlogopite : KMg 3 AlSi 3 O 10 (OH) 2
- Pyrophyllite Al 2 Si 4 O 10 (OH) 2
- Talc : Mg 3 Si 4 O 10 (OH) 2
- Tectosilicates
- Nesosilicates
See also
Related articles
External Links
- (En) French Society of Mineralogy and Crystallography
- (En) Minerals in France
- (En) Encyclopedia of World Mineral (definitions, properties, pictures and location)
- (En) Target Earth, mineralogy
- (En) French Association of Microminralogie
- (Fr) Virtual Gallery of Mineralogy at the Museum National d'Histoire Naturelle
- (Fr) Virtual Microscope at the University of North Carolina
