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Herkimer diamonds are double-terminated quartz crystals discovered within exposed outcrops of dolomite in and around Herkimer County, New York, and the Mohawk River Valley in the US. [ 1 ] [ 2 ] They are not diamonds ; the "diamond" in their name is due to both their clarity and well-formed faces.
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 ...
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. [9] Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral. The transformation ...
Ternary diagram showing the relative abundance of quartz, feldspar, and lithic grains and views of what selected compositions would look like. A QFL diagram or QFL triangle is a type of ternary diagram that shows compositional data from sandstones and modern sands, point counted using the Gazzi-Dickinson method. The abbreviations used are as ...
Little River rises north of Quartz Mountain in eastern Douglas County in the Umpqua National Forest. It flows west-northwest and joins the North Umpqua from the south at Glide, approximately 12 miles (19 km) east-northeast of Roseburg. The confluence is known as Colliding Rivers because of the nearly head-on angle at which the streams meet. [6]
QAPF diagram for classification of plutonic rocks. A QAPF diagram is a doubled-triangle plot diagram used to classify intrusive igneous rocks based on their mineralogy.The acronym QAPF stands for "Quartz, Alkali feldspar, Plagioclase, Feldspathoid (Foid)", which are the four mineral groups used for classification in a QAPF diagram.
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This sets it apart from rock crystal, amethyst, citrine, and the other varieties of crystalline quartz. Other members of the cryptocrystalline silica family include agate , carnelian , and onyx . Unlike many non-transparent silica minerals, it is the color of chrysoprase, rather than any pattern of markings, that makes it desirable.