Gemstones - MineralogyPage 2 of 8
General mineralogy
The mineralogy deals with the composition and structure of minerals and thus also of the precious stones. It is a very extensive and complicated science. We hope that we can get this part of course for all areas.
Hardness scale
Friedrich Mohs introduced a ten-part hardness scale. Here, the first is the softest mineral, it can be scratched from all other minerals. The tenth is the diamond mineral, it is so hard that it can be scratched by any other mineral.
The scoring also provides an excellent opportunity to check the authenticity of a gemstone. Each gemstone has a hardness according to its composition. Can the appropriate stone scratched with a lower mineral hardness, it is a fake!
Since you do not always have all 10 minerals while there are a few simple rules to determine the hardness.
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1 | Talc | with Fingernail scratched |
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2 | gypsum | with Fingernail scratched |
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3 | Calcite | with Copper coin scratched |
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4 | Fluorite | with Good knife can be scratched |
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5 | Apatite | with Knife scratched still |
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6 | Feldspar | with Steel file scratched |
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7 | Quartz | with Topaz scratched, scratched window glass, strikes sparks with steel |
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8 | Topaz | with Corundum scratched, scratched window glass, strikes sparks with steel |
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9 | Corundum | with Diamond scratched, scratched window glass, strikes sparks with steel |
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10 | Diamond | not scratched, strikes sparks with steel |
Mineral classes
Depending on the composition distinguish Gemstones in 9 Mineral classes.
1. Elements:
consist of the basic building blocks, the elements that make no connection
Example: Gold, Silver, Copper, Diamond
2. Sulfides:
Acid salts of hydrogen sulfide. Compounds of metals and Sulfur
Examples: galena, Chalcopyrite, Piemontite, pyrite
3. Halites:
Compounds with halogens such as fluorine, bromine, chlorine, iodine
Examples: Boleite, Fluorite, rock salt
4. Oxides:
Combustion products, combined with oxygen
Examples: Agate, Amethyst, rock crystal, citrine, hematite, jasper, opal, sapphire
5. Carbonates, nitrates and Borates:
Salts of carbonic acid, nitric acid and boric acid
Examples: aragonite, Azurite, calcite, magnesite, malachite, coral
6. Sulfates, chromates, Molybdates and tungstates:
Salts of sulfuric acid, chromic acid, and tungstic acid Molybdatsäure
Examples: barite, Celestine, Gipsspat, Desert Rose
7. Phosphates, arsenates and vanadates:
Salts of phosphoric acid, arsenic acid and Vandatsäure
Examples: Apatite, Turquoise
8. Silicates:
Combination of silicon and oxygen
Examples: Aquamarine, Feldspar, garnet, lapis lazuli, peridot, rhodolite, emerald
9 9. organic Connections:
Non-mineral, material is of organic origin
Examples: Alabaster, Amber, coral, obsidian, pearls
Crystal forms
| Cubic All sides are equal All axes are perpendicular to each |
Hexagonal Six-sided base All sides are equal and perpendicular to the Area |
| Tetragonal 2 sides are equal All axes are perpendicular to each |
Orthorhombic All sides are of different sizes All axes are perpendicular to each |
| Monoclinic All sides are of different sizes Only two axes are perpendicular to each |
Triclinic All sides are of different sizes All axes are not perpendicular to each other |
| Trigonal All sides are of different sizes Only two axes are perpendicular to each other, an angle is 120 degrees |
Light effects
Aventurescence:Reflections in feldspar and quartz by mineral and metal inclusions
Labradorscent:
Shiny metallic reflection in the entire color spectrum by Interference phenomenon in Entmischungslamellen
Opalescent:
Flat in shimmering blue and white
Cat's Eye Effect:
Lines of light by reflection
Adularisation:
Blue to white shimmer that moves when you move the stone
Star Effect:
Lines of light by reflection, which intersect
Iridescence:
Splitting the light into its spectral colors
Silk Gloss:
Gloss scale, caused by reflection
Books about Gemstones:
 
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