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2. Pegmatite - Wikipedia

   en.wikipedia.org/wiki/Pegmatite

   Pegmatite. A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than 1 cm (0.4 in) and sometimes greater than 1 meter (3 ft). Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic composition to granite.

3. Gemstone - Wikipedia

   en.wikipedia.org/wiki/Gemstone

   Gemstone. Group of precious and semiprecious stones—both uncut and faceted—including (clockwise from top left) diamond, uncut synthetic sapphire, ruby, uncut emerald, and amethyst crystal cluster. 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 ...

4. Desert rose (crystal) - Wikipedia

   en.wikipedia.org/wiki/Desert_rose_(crystal)

   A desert rose is an intricate rose -like formation of crystal clusters of gypsum or baryte, which include abundant sand grains. [1] The "petals" are crystals flattened on the c axis, fanning open in radiating clusters. The rosette crystal habit tends to occur when the crystals form in arid sandy conditions, [1] such as the evaporation of a ...

5. Quartz - Wikipedia

   en.wikipedia.org/wiki/Quartz

   Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO 4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO 2. Quartz is, therefore, classified structurally as a framework silicate mineral and ...

6. Facet - Wikipedia

   en.wikipedia.org/wiki/Facet

   Facet. Facets (/ ˈfæsɪt /) are flat faces on geometric shapes. The organization of naturally occurring facets was key to early developments in crystallography, since they reflect the underlying symmetry of the crystal structure. Gemstones commonly have facets cut into them in order to improve their appearance by allowing them to reflect light.

7. Crystal - Wikipedia

   en.wikipedia.org/wiki/Crystal

   Crystal. Crystals of amethyst quartz. Microscopically, a single crystal has atoms in a near-perfect periodic arrangement; a polycrystal is composed of many microscopic crystals (called "crystallites" or "grains"); and an amorphous solid (such as glass) has no periodic arrangement even microscopically. A crystal or crystalline solid is a solid ...