Orthoclase
Optical properties
Crystal System:	Monoclinic
Color in PPL:	Colorless, commonly with a dusty or cloudy appearance
Pleochroism:	N/A
Habit/Shape:	Can be anhedral or euhedral. Grains are commonly elongate with a tabular appearance.
Relief:	Low negative relief
Cleavage/Fracture Habit:	Has perfect cleavage on {001} and good cleavage on {010}. Cleavages intersect at 90°. It can be difficult to see cleavage in thin section due to orthoclase's low relief.
Twinning:	Typically displays carlsbad twinning. Baveno and manebach twins have also been reported in orthoclase.
Birefringence:	Up to first order white (roughly 0.007)
Extinction Habit/Angle:	Parallel extinction to cleavage
Length Slow/Fast:	N/A
Optic Sign:	Biaxial negative
2Vx:	40-70°
Alteration:	Commonly alters to sericite or clay.
Distinguishing Characteristics:	Distinguishable from microcline by a lack in gridiron twinning. Distinguishable from sanidine by a larger 2Vx.

Orthoclase (KAlSi₃O₈) is an important tectosilicate mineral, which forms igneous rock. It is also known as alkali feldspar and is common in granite and related rocks. Image File history File links Mineraly. ... In crystallography, the monoclinic crystal system is one of the 7 lattice point groups. ... PPL can stand for: An abbreviation for People, often used in IRC and Instant Messengers. ... Pleochroism is an optical phenomenon where due to double refraction of light by a colored gem or crystal, the light is divided into two paths which are polarized at a 90° angle to each other. ... Euhedral refers to well-formed crystals with sharp, easily-recognized faces. ... Euhedral refers to well formed crystals with sharp easily recognised faces. ... It has been suggested that twin boundary be merged into this article or section. ... Baveno, a town of Piedmont, Italy, on the west shore of Lago Maggiore, 13 miles North West of Arona by rail. ... A calcite crystal laid upon a paper with some letters showing the double refraction Birefringence, or double refraction, is the decomposition of a ray of light into two rays (the ordinary ray and the extraordinary ray) when it passes through certain types of material, such as calcite crystals, depending on... Sericite is a fine grained mica, either muscovite, illite, or paragonite. ... The Gay Head cliffs in Marthas Vineyard are made almost entirely of clay. ... Microcline (KAlSi3O8) is an important igneous rock forming tectosilicate mineral. ... The silicate minerals make up the largest and most important class of rock-forming minerals. ... Minerals are natural compounds formed through geological processes. ... Igneous rocks are formed when molten rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ... Lunar Ferroan Anorthosite #60025 (Plagioclase Feldspar). ... Quarrying granite for the Mormon Temple, Utah Territory. ...

Orthoclase is named based on the Greek for "straight fracture," because its two cleavages are at right angles to each other. Orthoclase crystallizes in the monoclinic crystal system. It has a hardness of 6, a specific gravity of 2.56-2.58, and a vitreous to pearly luster. It can be colored white, gray, yellow, pink, or red; rarely green. Twinned crystals are quite common. Orthoclase is a common constituent of most granites and other felsic igneous rocks and is often found in huge crystals and masses in pegmatite masses. In crystallography, the monoclinic crystal system is one of the 7 lattice point groups. ... The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... It has been suggested that twin boundary be merged into this article or section. ... Quartz crystal Copper(II) sulfate and iodine crystal Synthetic bismuth crystal Insulin crystals Gallium, a metal that easily forms large single crystals A huge monocrystal of potassium dihydrogen phosphate grown from solution by Saint-Gobain for the megajoule laser of CEA. In chemistry and mineralogy, a crystal is a solid... Quarrying granite for the Mormon Temple, Utah Territory. ... Felsic is a term used in geology to refer to silicate minerals, magmas, and rocks which are enriched in the lighter elements such as silica, oxygen, aluminium, sodium, and potassium. ... Volcanic rock on North America Plutonic rock on North America Igneous rocks are formed when rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ... This article or section does not cite its references or sources. ...

Adularia (from Adular) is found in low temperature hydrothermal deposits. When pearly and opalescent, orthoclase is called moonstone and is used in jewelry. These opalescent varieties are known to be an intergrowth of orthoclase and albite called perthite. A glassy kind of orthoclase, called sanidine, is typical of felsic volcanic rocks and is found in the trachytes of the Drachenfels, Germany. Adularia is a tectosilicate mineral with formula KAlSi3O8. ... Hydrothermal circulation in the oceans is the passage of the water through mid-ocean Ridge (MOR) systems. ... For other articles with similar names, see Opal (disambiguation). ... Insert non-formatted text hereMoonstone may refer to: go dawgs!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! #1 #1 #1 #1 #1!!!!!!!!!!!!!!!!!!!!! Moonstone, a type of gemstone (see orthoclase) The Moonstone, a novel by Wilkie Collins Moonstone Books, a publisher of graphic novels and comic books. ... Albite Albite is an alkali feldspar mineral. ... A perthite is a structural (perthitic structure) variety of the potassium feldspars microcline and orthoclase (KAlSi3O8). ... Orthoclase (KAlSi3O8) is an important igneous rock forming tectosilicate mineral. ... This article is about volcanoes in geology. ... A sample of trachyte Trachyte is an igneous, volcanic rock with an aphanitic to porphyritic texture. ... There are several locations (mountain tops and castles) named Drachenfels (German : dragons rock): Drachenfels (Siebengebirge) Drachenfels (Pfälzer Wald) Drachenfels (Wasgau) This is a disambiguation page: a list of articles associated with the same title. ...

Together with the other potassium feldspars orthoclase is a common raw material for the manufacture of some glasses, some ceramics, such as porcelain, and as a constituent of scouring powder. Lunar Ferroan Anorthosite #60025 (Plagioclase Feldspar). ... Glass can be made transparent and flat, or into other shapes and colors as shown in this sphere from the Verrerie of Brehat in Brittany. ... Fixed Partial Denture, or Bridge The word ceramic is derived from the Greek word κεραμικός (keramikos). ... “Fine China” redirects here. ...

It is the state gem of Florida. List of U.S. state minerals, rocks, stones, and gemstones. ... Official language(s) English Capital Tallahassee Largest city Jacksonville Largest metro area Miami Area  Ranked 22nd  - Total 65,795[1] sq mi (170,304[1] km²)  - Width 361 miles (582 km)  - Length 447 miles (721 km)  - % water 17. ...

See also

• List of minerals

Gem animals. ...

References

• Alkali feldspars U. Texas
• Mindat