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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. Smoky quartz - Wikipedia

   en.wikipedia.org/wiki/Smoky_quartz

   Smoky quartz is a brownish grey, translucent variety of quartz that ranges in clarity from almost complete transparency to an almost-opaque brownish-gray or black crystals. [6] The color of smoky quartz is produced when natural radiation, emitted from the surrounding rock, activates color centers around aluminum impurities within the ...

4. Prasiolite - Wikipedia

   en.wikipedia.org/wiki/Prasiolite

   Prasiolite (also known as green quartz, green amethyst or vermarine) is a green variety of quartz. Since 1950, almost all natural prasiolite has come from a small Brazilian mine, [citation needed] but it has also been mined in the Lower Silesia region of Poland. Naturally occurring prasiolite has also been found in the Thunder Bay area of ...

5. Amethyst - Wikipedia

   en.wikipedia.org/wiki/Amethyst

   Green quartz is sometimes called green amethyst; the scientific name is prasiolite. [9] Other names for green quartz are vermarine and lime citrine. Amethyst frequently shows color zoning, with the most intense color typically found at the crystal terminations. One of gem cutters' tasks is to make a finished product with even color. Sometimes ...

6. Quartzite - Wikipedia

   en.wikipedia.org/wiki/Quartzite

   Quartzite is a very hard rock composed predominantly of an interlocking mosaic of quartz crystals. The grainy, sandpaper-like surface is glassy in appearance. Minor amounts of former cementing materials, iron oxide, silica, carbonate and clay, often migrate during recrystallization, causing streaks and lenses to form within the quartzite. [1]

7. Citrine (colour) - Wikipedia

   en.wikipedia.org/wiki/Citrine_(colour)

   Citrine / ˈ s ɪ t r iː n / is a colour, the most common reference for which is certain coloured varieties of quartz which are a medium deep shade of golden yellow. Citrine has been summarized at various times as yellow, greenish-yellow, brownish yellow or orange. [2] The original reference point for the citrine colour was the citron fruit.

8. Tiger's eye - Wikipedia

   en.wikipedia.org/wiki/Tiger's_eye

   Tiger's eye (also called tiger eye) is a chatoyant gemstone that is usually a metamorphic rock with a golden to red-brown colour and a silky lustre.As members of the quartz group, tiger's eye and the related blue-coloured mineral hawk's eye gain their silky, lustrous appearance from the parallel intergrowth of quartz crystals and altered amphibole fibres that have mostly turned into limonite.

9. Gemstone - Wikipedia

   en.wikipedia.org/wiki/Gemstone

   Most green quartz (Oro Verde) are also irradiated to achieve the yellow-green color. Diamonds are mainly irradiated to become blue-green or green, although other colors are possible. When light-to-medium-yellow diamonds are treated with gamma rays they may become green; with a high-energy electron beam, blue.