Only 1.60 euros about for Mineral ! Lot 11 Pieces Citrine Quartz Raw Minerals Stones Rocks for Collection, 100 gr in total, cm 2-3.8.
The lot is just that of the photo.
Also available in single pieces, at this link.
Silicon Dioxide (SiO2).
Citrine Quartz is a variety of Quartz whose color is due to trivalent iron impurities (about 40 parts per million) in the crystalline lattice (it changes the oxidation state of iron with respect to amethyst quartz).
Citrine quartz, endowed with particularly valuable colors and transparencies, has been used as a gem or ornamental stone for over three thousand years; in the past it was often confused with topaz, which has similar colours, and was therefore (and still is) improperly called quartz topaz, madeira, madeira topaz, Spanish topaz, Saxon topaz and others.
Citrine Quartz is found in volcanic rocks, often in cavities, forming geodes, but also in quartz veins (massive citrine). The main deposits are in Brazil, Madagascar and the United States.
Quartz (silicon dioxide, SiO2, is the second most abundant mineral in the earth's crust (about 12% of its volume) after feldspars.
The etymology of the name is not certain, but for the ancient Greeks quartz was defined as crystal (from the Greek κρύσταλλος, krýstallos, ice). In fact, they considered this mineral a variety of ice cold to the point that it could no longer be dissolved.
Quartz has a crystalline structure made up of silicon and oxygen tetrahedrons joined together by the 4 vertices to form spirals. The habitus (the shape) is a hexagonal prism with the faces of two rhombohedrons at the vertices arranged in such a way as to form a hexagonal bipyramid. Quartz can have an elongated prismatic shape.
Quartz is a common constituent of acidic intrusive magmatic rocks, among which the best known is granite; it is also abundant as a component of sedimentary rocks, preferably in sandstones due to its high resistance to chemical degradation by atmospheric agents and its insolubility in water and in metamorphic rocks.
Being one of the most common minerals of the earth's crust, quartz has a large number of different varieties, with macroscopic crystals visible to the naked eye, or crystals so small as to be visible only under a microscope or even invisible with such an instrument. Although many of the variety names have historically come from the colors of the mineral, current scientific naming schemes refer primarily to the microstructure of the mineral. Usually, but not always, color is a secondary identifier.
In addition to hyaline quartz, perfectly colorless and clear, there are numerous other varieties of quartz, many of which are for sale on our site:
Chalcedony, Agate, Moss Agate, Chrysoprase, Onyx, Carnelian, Sardonyx, Jasper, Heliotrope, Aventurine, Tiger's Eye, Cat's Eye, Bull's Eye, Hawk's Eye, Amethyst, Ametrine, Citrine or Madeira, Rose Quartz, Quartz blue, Prasiolite, Milky Quartz, Smoky Quartz, Morion, Rutilated Quartz, Tourmaline Quartz, Dendritic Quartz, etc.
Quartz is a material with remarkable chemical stability and is resistant to acids except hydrofluoric acid. It has high hardness (7 on the Mohs scale), mechanical and heat resistance. The quartz has no cleavage. Some physical properties of quartz crystals are piezoelectricity and pyroelectricity, i.e. the ability to electrically polarize the opposite faces of the crystal following the mechanical deformation caused by compression or after heating. From an optical point of view, quartz has high transmissibility in the visible and especially in the ultraviolet.
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