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2. Quartz - Wikipedia

   en.wikipedia.org/wiki/Quartz

   A synthetic quartz crystal grown by the hydrothermal method, about 19 centimetres (7.5 in) long and weighing about 127 grams (4.5 oz) Not all varieties of quartz are naturally occurring. Some clear quartz crystals can be treated using heat or gamma-irradiation to induce color where it would not otherwise have occurred naturally. Susceptibility ...

3. Crystal - Wikipedia

   en.wikipedia.org/wiki/Crystal

   Crystals of amethyst quartz Microscopically, ... Likewise, the only difference between ruby and sapphire is the type of impurities present in a corundum crystal.

4. Crystal structure - Wikipedia

   en.wikipedia.org/wiki/Crystal_structure

   The relationship between d-electrons and crystal structure thus becomes apparent. [20] ... Quartz is one of the several crystalline forms of silica, SiO 2.

5. Cristobalite - Wikipedia

   en.wikipedia.org/wiki/Cristobalite

   Cristobalite (/ k r ɪ ˈ s t oʊ b ə ˌ l aɪ t /) is a mineral polymorph of silica that is formed at very high temperatures. It has the same chemical formula as quartz, Si O 2, but a distinct crystal structure.

6. Mineral - Wikipedia

   en.wikipedia.org/wiki/Mineral

   These differences arise corresponding to how aluminium is coordinated within the crystal structure. In all minerals, one aluminium ion is always in six-fold coordination with oxygen. Silicon, as a general rule, is in four-fold coordination in all minerals; an exception is a case like stishovite (SiO 2 , an ultra-high pressure quartz polymorph ...

7. Silicon dioxide - Wikipedia

   en.wikipedia.org/wiki/Silicon_dioxide

   These crystals are a source of very pure quartz for use in electronic applications. [15] Above the critical temperature of water 647.096 K (373.946 °C; 705.103 °F) and a pressure of 22.064 megapascals (3,200.1 psi) or higher, water is a supercritical fluid and solubility is once again higher than at lower temperatures.