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  2. Amethyst - Wikipedia

    en.wikipedia.org/wiki/Amethyst

    ions that replace Si in the lattice to lose an electron and form a [FeO 4] 0 color center. [5] Amethyst is a three-dimensional network of tetrahedra where the silicon atoms are in the center and are surrounded by four oxygen atoms located at the vertices of a tetrahedron. This structure is quite rigid and results in quartz's hardness and ...

  3. Mineralogy - Wikipedia

    en.wikipedia.org/wiki/Mineralogy

    Mineralogy applies principles of chemistry, geology, physics and materials science to the study of minerals. Mineralogy [n 1] is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts.

  4. Peridot - Wikipedia

    en.wikipedia.org/wiki/Peridot

    Geologically [ edit ] Olivine , of which peridot is a type, is a common mineral in mafic and ultramafic rocks , often found in lava and in peridotite xenoliths of the mantle , which lava carries to the surface; however, gem-quality peridot occurs in only a fraction of these settings.

  5. Quartzite - Wikipedia

    en.wikipedia.org/wiki/Quartzite

    Quartzite can have a grainy, glassy, sandpaper-like surface. Quartzite is a hard, non-foliated metamorphic rock which was originally pure quartz sandstone. [1] [2] Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts.

  6. Geological formation - Wikipedia

    en.wikipedia.org/wiki/Geological_formation

    The names must not duplicate previous formation names, so, for example, a newly designated formation could not be named the Kaibab Formation, since the Kaibab Limestone is already established as a formation name. The first use of a name has precedence over all others, as does the first name applied to a particular formation. [6]

  7. Flint - Wikipedia

    en.wikipedia.org/wiki/Flint

    Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, [1] [2] categorized as the variety of chert that occurs in chalk or marly limestone. Historically, flint was widely used to make stone tools and start fires. Flint occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones.

  8. Liesegang rings (geology) - Wikipedia

    en.wikipedia.org/wiki/Liesegang_rings_(geology)

    [5] As Ostwald suggests, there is a localized formation of crystal seeds that occurs when the right level of supersaturation is reached, and once the crystal seeds form, the growth of the crystals is believed to lower the supersaturation level of fluids in pore spaces surrounding the crystals, thus mineralization that occurs after the initial ...

  9. Trap rock - Wikipedia

    en.wikipedia.org/wiki/Trap_rock

    The East Rock trap rock ridge overlooking New Haven, Connecticut, U.S. Trap rock forming a characteristic pavement, Giant's Causeway, Northern Ireland Trap rock cliff overlooking the Hudson River from an overlook on the Hudson Palisades in Bergen County, New Jersey, U.S. Trap rock forming a characteristic stockade wall, Giant's Causeway, Northern Ireland

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