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  2. Gypsum - Wikipedia

    en.wikipedia.org/wiki/Gypsum

    Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 4 ·2H 2 O. [4] It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk chalk.

  3. Benitoite - Wikipedia

    en.wikipedia.org/wiki/Benitoite

    Benitoite occurs in a number of isolated locations globally, but gemstone quality material has only been found in California at the Benito Gem Mine where it was first discovered. It has been correctly identified in Montana , Arkansas , Japan , and Australia although they formed under slightly different conditions and only grow large enough to ...

  4. Category:Gemstone mines - Wikipedia

    en.wikipedia.org/wiki/Category:Gemstone_mines

    This category is for mines for cardinal gems other than Diamond, ie amethyst, emerald, ruby & sapphire, and also opal mines (see Gemstone). Subcategories This category has the following 3 subcategories, out of 3 total.

  5. Blue John (mineral) - Wikipedia

    en.wikipedia.org/wiki/Blue_John_(mineral)

    One source is the Deqing Fluorite Mine, in Deqing County, Zhejiang Province, [1]: 40 the only source (other than in Derbyshire) that has an ornamental craft based upon it. [ 1 ] : 38 However, although this fluorite is similar to Blue John its banding is straighter and it contains colours not associated with Blue John, suggesting they are ...

  6. Hiddenite Gem Mines - Wikipedia

    en.wikipedia.org/wiki/Hiddenite_Gem_Mines

    This a public gem mine located in the Piedmont of North Carolina in Alexander County, specifically in the town of Hiddenite. [2] At the mine, more than 63 different types of gems and minerals can be found including emeralds, amethyst, sapphire, aquamarine, topaz, garnet, as well as the stone Hiddenite, which is a stone only found in this local ...

  7. Hiddenite - Wikipedia

    en.wikipedia.org/wiki/Hiddenite

    Kunz noted that the finest crystal recovered prior to 1892 measured 68 mm tall, and could have cut a gem of 5.5ct estimated weight. The size of most cut gems were small, with a 2ct hiddenite in the Augustus C. Hamlin collection being considered among the finest of the large stones. The coloring agent is chromium. Colors can gradually fade.

  8. Cummingtonite - Wikipedia

    en.wikipedia.org/wiki/Cummingtonite

    2 for magnesiocummingtonite to the iron rich grunerite endmember Fe 7 Si 8 O 22 (OH) 2. Cummingtonite is used to describe minerals of this formula with between 30 and 70 per cent Fe 7 Si 8 O 22 (OH) 2. Thus, cummingtonite is the series intermediate. Manganese also substitutes for (Fe,Mg) within cummingtonite amphibole, replacing B site atoms.

  9. Kimberlite - Wikipedia

    en.wikipedia.org/wiki/Kimberlite

    It is named after the town of Kimberley in South Africa, where the discovery of an 83.5-carat (16.70 g) diamond called the Star of South Africa in 1869 spawned a diamond rush and led to the excavation of the open-pit mine called the Big Hole. Previously, the term kimberlite has been applied to olivine lamproites as Kimberlite II, however this ...