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  2. Stibiotantalite - Wikipedia

    en.wikipedia.org/wiki/Stibiotantalite

    Stibiotantalite is primarily used as a gemstone. [4] These gems are vivid, shiny, and golden-brown. These gems come between 0.73 carats and 6.34 carats, with the average being 3.54. These gems are similar in appearance to sphalerite, but they are brown instead of orange. While stibiotantalite and tantalite are similar, stibiotantalite is softer ...

  3. List of gemstones by species - Wikipedia

    en.wikipedia.org/wiki/List_of_gemstones_by_species

    This is a list of gemstones, organized by species and types. Minerals. There are over 300 types of minerals that have been used as gemstones. Such as: A–B

  4. Gemstone - Wikipedia

    en.wikipedia.org/wiki/Gemstone

    A gemstone (also called a fine gem, jewel, precious stone, semiprecious stone, or simply gem) is a piece of mineral crystal which, when cut or polished, is used to make jewelry or other adornments.

  5. Russellite (mineral) - Wikipedia

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

    Russellite is a bismuth tungstate mineral with the chemical formula Bi 2 WO 6. [2] It crystallizes in the orthorhombic crystal system.Russellite is yellow or yellow-green in color, with a Mohs hardness of 3 + 1 ⁄ 2.

  6. Carat (mass) - Wikipedia

    en.wikipedia.org/wiki/Carat_(mass)

    The carat (ct) is a unit of mass equal to 200 mg (0.00705 oz; 0.00643 ozt), which is used for measuring gemstones and pearls. The current definition, sometimes known as the metric carat , was adopted in 1907 at the Fourth General Conference on Weights and Measures , [ 1 ] [ 2 ] and soon afterwards in many countries around the world.

  7. Natrolite - Wikipedia

    en.wikipedia.org/wiki/Natrolite

    Natrolite is a tectosilicate mineral species belonging to the zeolite group. It is a hydrated sodium and aluminium silicate with the formula Na 2 Al 2 Si 3 O 10 ·2H 2 O. [4] The type locality is Hohentwiel, Hegau, Germany.

  8. Hierarchy of precious substances - Wikipedia

    en.wikipedia.org/wiki/Hierarchy_of_precious...

    The measurement of sales of popular music starts high relative to the wedding anniversary scale, concentrating on gold and platinum (see gold album).Likewise, credit card companies usually have a "gold card" and a "platinum card" (many formerly had a "silver card" then followed by a "gold card", but due to similarity in appearance between silver and platinum these were often discontinued with ...

  9. List of individual gemstones - Wikipedia

    en.wikipedia.org/wiki/List_of_individual_gemstones

    Bahia Emerald [2]; Carolina Emperor, [3] [4] 310 carats uncut, 64.8 carats cut; discovered in the United States in 2009, resides in the North Carolina Museum of Natural Sciences, Raleigh, NC, US