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2. Quartz - Wikipedia

   en.wikipedia.org/wiki/Quartz

   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 ...

3. Fused quartz - Wikipedia

   en.wikipedia.org/wiki/Fused_quartz

   Fused quartz, fused silica or quartz glass is a glass consisting of almost pure silica (silicon dioxide, SiO 2) in amorphous (non- crystalline) form. This differs from all other commercial glasses, such as soda-lime glass, lead glass, or borosilicate glass, in which other ingredients are added which change the glasses' optical and physical ...

4. Geode - Wikipedia

   en.wikipedia.org/wiki/Geode

   Geode. A geode (/ ˈdʒiː.oʊd /; from Ancient Greek γεώδης (geṓdēs) 'earthlike') is a geological secondary formation within sedimentary and volcanic rocks. Geodes are hollow, vaguely spherical rocks, in which masses of mineral matter (which may include crystals) are secluded. The crystals are formed by the filling of vesicles in ...

5. Chert - Wikipedia

   en.wikipedia.org/wiki/Chert

   Chert (/ tʃ ɜːr t /) is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, [1] the mineral form of silicon dioxide (SiO 2). [2] Chert is characteristically of biological origin, but may also occur inorganically as a chemical precipitate or a diagenetic replacement, as in petrified wood.

6. Transparent ceramics - Wikipedia

   en.wikipedia.org/wiki/Transparent_ceramics

   Transparent ceramics. Transparent spinel (MgAl 2 O 4) ceramic is used traditionally for applications such as high-energy laser windows because of its excellent transmission in visible wavelengths and mid-wavelength infrared (0.2–5.0 μm) when combined with selected materials – source: U.S. Naval Research Laboratory [citation needed] Many ...

7. Moss agate - Wikipedia

   en.wikipedia.org/wiki/Moss_agate

   Moss agate. Moss agate is a semi-precious gemstone formed from silicon dioxide. It is a form of chalcedony which includes minerals of a green color embedded in the stone, forming filaments and other patterns suggestive of moss. [1] The field is a clear or milky-white quartz, and the included minerals are mainly oxides of manganese or iron.