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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. 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.

  4. Mohs scale - Wikipedia

    en.wikipedia.org/wiki/Mohs_scale

    Mohs hardness kit, containing one specimen of each mineral on the ten-point hardness scale. The Mohs scale (/ m oʊ z / MOHZ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of minerals through the ability of harder material to scratch softer material.

  5. Cobaltite - Wikipedia

    en.wikipedia.org/wiki/Cobaltite

    Pyramidal (mm2) (same H-M symbol) Space group: Pc2 1 b: Unit cell: a = 5.582 Å, b = 5.582 Å, c = 5.582 Å; Z = 4: Identification; Color: Reddish silver white, violet steel gray to black: Crystal habit: Granular to massive, rarely as striated crystals, pseudocubic. Twinning: About [111] creating pseudo-cubic forms and striations: Cleavage ...

  6. 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 ...

  7. Orthorhombic crystal system - Wikipedia

    en.wikipedia.org/wiki/Orthorhombic_crystal_system

    In crystallography, the orthorhombic crystal system is one of the 7 crystal systems.Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with a rectangular base (a by b) and height (c), such that a, b, and c are distinct.

  8. Bertrandite - Wikipedia

    en.wikipedia.org/wiki/Bertrandite

    Bertrandite is a beryllium sorosilicate hydroxide mineral with composition: Be 4 Si 2 O 7 (OH) 2.Bertrandite is a colorless to pale yellow orthorhombic mineral with a hardness of 6–7.

  9. Boracite - Wikipedia

    en.wikipedia.org/wiki/Boracite

    Boracite is a magnesium borate mineral with formula: Mg 3 B 7 O 13 Cl.It occurs as blue green, colorless, gray, yellow to white crystals in the orthorhombic - pyramidal crystal system.