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  2. Crystal - Wikipedia

    en.wikipedia.org/wiki/Crystal

    As of 1999, the world's largest known naturally occurring crystal is a crystal of beryl from Malakialina, Madagascar, 18 m (59 ft) long and 3.5 m (11 ft) in diameter, and weighing 380,000 kg (840,000 lb). [12] Some crystals have formed by magmatic and metamorphic processes, giving origin to large masses of crystalline rock.

  3. Quartz - Wikipedia

    en.wikipedia.org/wiki/Quartz

    Naturally occurring quartz crystals of extremely high purity, necessary for the crucibles and other equipment used for growing silicon wafers in the semiconductor industry, are expensive and rare. These high-purity quartz are defined as containing less than 50 ppm of impurity elements. [ 83 ]

  4. Cubic zirconia - Wikipedia

    en.wikipedia.org/wiki/Cubic_zirconia

    During synthesis zirconium oxide naturally forms monoclinic crystals, which are stable under normal atmospheric conditions. A stabilizer is required for cubic crystals (taking on the fluorite structure ) to form, and remain stable at ordinary temperatures; typically this is either yttrium or calcium oxide, the amount of stabilizer used ...

  5. Opal - Wikipedia

    en.wikipedia.org/wiki/Opal

    "Natural" opal refers to polished stones consisting wholly of precious opal. Opals too thin to produce a "natural" opal may be combined with other materials to form "composite" gems. An opal doublet consists of a relatively thin layer of precious opal, backed by a layer of dark-colored material, most commonly ironstone, dark or black common ...

  6. Moissanite - Wikipedia

    en.wikipedia.org/wiki/Moissanite

    As natural sources of silicon carbide are rare, and only certain atomic arrangements are useful for gemological applications, North Carolina–based Cree Research, Inc., founded in 1987, developed a commercial process for producing large single crystals of silicon carbide. Cree is the world leader in the growth of single crystal silicon carbide ...

  7. Crystallization - Wikipedia

    en.wikipedia.org/wiki/Crystallization

    The nature of the crystallization process is governed by both thermodynamic and kinetic factors, which can make it highly variable and difficult to control. Factors such as impurity level, mixing regime, vessel design, and cooling profile can have a major impact on the size, number, and shape of crystals produced.

  8. Mineral - Wikipedia

    en.wikipedia.org/wiki/Mineral

    Crystals of serandite, natrolite, analcime, and aegirine from Mont Saint-Hilaire, Quebec, Canada. In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.

  9. Corundum - Wikipedia

    en.wikipedia.org/wiki/Corundum

    Corundum is a crystalline form of aluminium oxide (Al 2 O 3) typically containing traces of iron, titanium, vanadium, and chromium. [3] [4] It is a rock-forming mineral.It is a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. [7]