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  2. Porphyry (geology) - Wikipedia

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

    "Imperial Porphyry" from the Red Sea Mountains of Egypt A waterworn cobble of porphyry Rhyolite porphyry from Colorado; scale bar in lower left is 1 cm (0.39 in). Porphyry (/ ˈ p ɔːr f ə r i / POR-fə-ree) is any of various granites or igneous rocks with coarse-grained crystals such as feldspar or quartz dispersed in a fine-grained silicate-rich, generally aphanitic matrix or groundmass.

  3. Charoite - Wikipedia

    en.wikipedia.org/wiki/Charoite

    Charoite (/ tʃ æ r oʊ. aɪ t / CHAR-ow-ait) is a rare silicate mineral with the chemical composition K(Ca,Na) 2 Si 4 O 10 (OH,F)•H 2 O, first described in 1978.It is named after the Chara River, despite its being 70 kilometres (43 mi) away from the discovery place.

  4. Purpurite - Wikipedia

    en.wikipedia.org/wiki/Purpurite

    Purpurite is a manganese phosphate mineral with the formula MnPO 4, with varying amounts of iron depending upon its source. It occurs in color ranges from brownish black via purple and violet to dark red. [3] Purpurite forms a series with the iron-bearing endmember heterosite, FePO 4. [4]

  5. List of U.S. state minerals, rocks, stones and gemstones

    en.wikipedia.org/wiki/List_of_U.S._state...

    Leaders of states in the U.S. which have significant mineral deposits often create a state mineral, rock, stone or gemstone to promote interest in their natural resources, history, tourism, etc. Not every state has an official state mineral, rock, stone and/or gemstone, however.

  6. List of minerals - Wikipedia

    en.wikipedia.org/wiki/List_of_minerals

    Amethyst (purple variety of quartz) Ametrine (variety of quartz) Ammolite (organic; also a gemstone) Amosite (asbestiform grunerite) Antozonite (variety of fluorite) Anyolite (metamorphic rock - zoisite, ruby, and hornblende) Aquamarine (light blue variety of beryl) Argentite (high temperature form of acanthite) Asbestos (fibrous serpentine- or ...

  7. Blue John (mineral) - Wikipedia

    en.wikipedia.org/wiki/Blue_John_(mineral)

    Blue John (also known as Derbyshire Spar) is a semi-precious mineral, a rare form of fluorite with bands of a purple-blue or yellowish colour. In the United Kingdom it is found only at Blue John Cavern and Treak Cliff Cavern at Castleton in Derbyshire. During the 19th century, it was mined for its ornamental value, and mining continues on a ...

  8. Portal:Minerals - Wikipedia

    en.wikipedia.org/wiki/Portal:Minerals

    A rock may consist of one type of mineral or may be an aggregate of two or more different types of minerals, spacially segregated into distinct phases. Some natural solid substances without a definite crystalline structure, such as opal or obsidian , are more properly called mineraloids .

  9. Amethyst - Wikipedia

    en.wikipedia.org/wiki/Amethyst

    The ideal grade, called "Deep Siberian", has a primary purple hue of around 75–80%, with 15–20% blue and (depending on the light source) red secondary hues. [7] "Rose de France" is defined by its markedly light shade of the purple, reminiscent of a lavender / lilac shade. These pale colors were once considered undesirable, but have recently ...