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2. Quartz - Wikipedia

   en.wikipedia.org/wiki/Quartz

   Quartz is, therefore, classified structurally as a framework silicate mineral and compositionally as an oxide mineral. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar. [10] Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral. The transformation ...

3. 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.

4. 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 ...

5. Chalcedony - Wikipedia

   en.wikipedia.org/wiki/Chalcedony

   Chalcedony's standard chemical structure (based on the chemical structure of quartz) is SiO 2 (silicon dioxide). Chalcedony has a waxy luster, and may be semitransparent or translucent. It can assume a wide range of colors, but those most commonly seen are white to gray, grayish-blue or a shade of brown ranging from pale to nearly black.

6. 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.

7. Jasper - Wikipedia

   en.wikipedia.org/wiki/Jasper

   Jasper, an aggregate of microgranular quartz and/or cryptocrystalline chalcedony and other mineral phases, [1] [2] is an opaque, [3] impure variety of silica, usually red, yellow, brown or green in color; and rarely blue. The common red color is due to iron(III) inclusions. Jasper breaks with a smooth surface and is used for ornamentation or as ...

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. Prasiolite - Wikipedia

   en.wikipedia.org/wiki/Prasiolite

   The word prasiolite literally means "scallion green-colored stone" and is derived from Greek πράσον prason meaning "leek" and λίθος lithos meaning "stone". The mineral was given its name due to its green-colored appearance. Natural prasiolite is a very light, translucent green. Darker green quartz is generally the result of ...