alert("Could not find the printReady section in the HTML"); feldspars). Feldspars make up more than half of Earths crust, and professional literature about them constitutes a large percentage of the literature of mineralogy. }. { Mohs scale hardness 6 (defining mineral) Luster: Vitreous, pearly on cleavage surfaces Streak: white Diaphaneity: Transparent to translucent Specific gravity: 2.552.63 Optical properties The res The gem known as moonstone is largely composed of orthoclase. Oxford Co; at Cornog, Chester Co., and Blue Hill and Lieperville, Delaware Co., It can be difficult to "); Co.; in Colorado, on Mt. Drag2 - Resize Gem crystals from Ampandrandava, Fianarantsoa, and Itrongay, near I - Indicies { At 400 degrees C or less, microcline is the stable structure for KAlSi3O8. _uacct = "UA-3067463-1"; Compositions of foremost elements in commonplace feldspars may be expressed in terms of 3 endmembers: potassium feldspar (K-spar) endmember KAlSi3O8, albite endmember NaAlSi3O8, anorthite endmember CaAl2Si2O8. Orthoclase is an important silicate or a rock-forming mineral that forms in igneous rocks. Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern. if (headTags.length > 0) Mineral Group: Feldspar (alkali) group; (Al,Si) commonly only partially ordered. Orthoclase forms at intermediate temperatures between the stability fields of sanidine and microcline. General Category Silicate mineral Chemical formula KAlSi3O8 From Baveno, Piedmont, in the Ptschtal, Orthoclase, or orthoclase feldspar (endmember formula KAlSi3O8), is an important tectosilicate mineral which forms igneous rock. } It is also cut as a gemstone. Optical Properties: Transparent to translucent. Widespread. if (gAutoPrint) It may also occur in massive form. Link to . Betroka, Madagascar. At Tanokamiyama, Shiga Prefecture, Healing Properties . 7.23. It occurs in different ways, usually, by crystallization of magma. & Series: Dimorphous with microcline; forms a Help on Above, Colville A A , Ribbe P H , American Mineralogist , 53 (1968) p.25-37, The crystal structure of an adularia and a refinement of the structure of, orthoclase, Note: Spencer B, variety adularia, GRapi = 200.97 (Gamma Ray American Petroleum Institute Units) The common feldspar of granites, granite pegmatites, and syenites. When viewed under a polarizing microscope, microcline exhibits a minute multiple twinning which forms a grating-like structure that is unmistakable. It is a type of potassium feldspar, also known as K-feldspar.The gem known as moonstone (see below) is largely composed of orthoclase. It can be difficult to see cleavage in thin section due to orthoclase's low relief. Green orthoclase (Precambrian; Southern Cross, about 11 to 12 km north of Broken Hill, far-western New South Wales, southeastern Australia) (15120707951).jpg 3,008 2,000; 2.62 MB Harvard Museum of Natural History. Orthoclase has several commercial uses. This group of minerals includes tectosilicates. The vibration direction of the fastest ray is X; the slowest is z. B - Bonds On/Off S - Stereo Pair on/off Zillertal, Tirol, Austria. Name: From the Greek for straight and fracture, in allusion to the urchinTracker(); Print or Cut-and-Paste your Orthoclase Specimen Label here : S - Stereo html += printReadyElem.innerHTML; good cleavage on {010}. It is a major component of granite its pink crystals give granite its typical color. M - Menu The name is from the Ancient Greek for "straight fracture," because its two cleavage planes are at right angles to each other. } Solid solutions among albite and anorthite are called plagioclase,or greater nicely plagioclase feldspar. else printWin.document.open(); At Epprechtstein, Albite, muscovite, biotite, hornblende, schorl, beryl. var html = '\n\n'; Intrusive and extrusive igneous, and metamorphic rocks. RMB - Cycle Display Modes Named at the beginning orthoclase, orthose, its french name, As one of the constituents of the moonstone, it has some of its properties, Optical properties. return; Birefringence: From Cornwall, It is dis-tinguished from sanidine by 2V and from micro-cline by its lack of plaid twinning. Fabre Minerals, Mouse This mineral is important in ceramics, to make the item itself and as a glaze. Common world wide occurrences. Japan. Trentino-Alto Adige, and at San Piero in Campo, Elba, Italy. Color: Colorless, white, gray, pale yellow, esh-red, green; colorless in thin section; may exhibit opalescence or schiller iridescence. Orthoclase, or orthoclase feldspar (endmember formula K Al Si 3 O 8), is an important tectosilicate mineral which forms igneous rock.The name is from the Greek for "straight fracture," because its two cleavage planes are at right angles to each other. Orthoclase is used in the manufacture of glass and ceramics; occasionally, transparent crystals are cut as gems. Learn more about the properties { { } Location: Rhonegletscher, Switzerland. While slowly cooling within the earth, sodium-rich albite lamellae form by exsolution, enriching the remaining orthoclase with potassium. Scale: 1.3 x 1.2 cm. Ask about Orthoclase here : alert("Sorry, the print ready feature is only available in modern browsers. Location: Zarzalejo, Madrid. Orthoclase is a highly beneficial crystal for reversing the declining processes in our body. Microcline is identical to orthoclase in many physical properties, and can be distinguished by x-ray or optical examination. Specimens are abundant in igneous rocks rich in potassium or silica, in pegmatites, and in gneisses. Optical properties and x-ray techniques are the only sure ways to distinguish orthoclase from sanidine, microcline and anorthoclase. In the USA, from Maine, at Paris and Buckeld, In cavities in basalts; in high-grade metamorphic rocks and as a result of potassic hydrothermal alteration; also authigenic and detrital. Prismatic - Crystals Shaped like Slender Prisms (e.g. printWin.document.write(html); Massive - Granular - Common texture observed in granite and other igneous rock. Common as Carlsbad, Baveno and Mindat.org's Discussion Groups Fine examples from St. } var printWin = window.open("","printSpecial", 'toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=yes,copyhistory=yes,width=350,height=350'); rock cooled quickly. Warning: this large pop-up is very compute intensive and These three minerals form the Potassium Feldspar group. Former Bally Museum collection. Fabre Minerals, Comments: Gemmy, twinned adularia (orthoclase) specimen on matrix. Orthoclase is often confused with quartz - try looking for cloudy patches on individual crystals in plain polarized light which indicate weathering of the crystal. else Pennsylvania. Biaxial (-), a=1.518, b=1.522, g=1.523-1.524, bire=0.0050-0.0060, 2V(Calc)=52-70, 2V(Meas)=65-75. Also take notice of the right angle cleavage. Manebach. after Perkins, 306 Its two cleavage planes are perpendicular to each other, which gives it the look of a straight fracture, which is known as Orthoclase in Greek, and hence the specific name . Optical Properties of Orthoclase; Refractive Index: 1.518 to 1.536. Luster: Vitreous (Glassy) Streak: white : Optical Properties of Orthoclase : Gladstone-Dale: CI meas= 0.011 (Superior) - where the CI = (1-KPDmeas/KC) CI calc= 0.007 (Superior) - where the CI = (1-KPDcalc/KC) KPDcalc= 0.2044,KPDmeas= 0.2036,KC= 0.2058 Ncalc = 1.52 - 1.53 : Optical Data: In the 184 relations. Optical properties and x-ray techniques are the only sure ways to distinguish orthoclase from sanidine, microcline and anorthoclase. It is polymorphous with the minerals Microcline and Sanidine. Optical Properties: PPL: Colorless Non-pleochroic Low relief If altered, may display brownish speckling or clouding: XPL: 1 st order gray Uneven stripes or wisps If altered, may look colorfully speckled: : 0.007: Twinning: Penetration and contact twins are common. var headTags = document.getElementsByTagName("head"); In California, from the Pala and Mesa Grande districts, San Diego It Help on Above. From Guanajuato, Mexico. html += '\n\n'; see cleavage in thin section due to orthoclases low relief. Not only that, it will help you prevent the fear of getting old and make you understand that the Spirit is always staying young no matter in what condition your physical body is. P - Polyhedra On/Off Orthoclase. orthoclase.pdf - Free download as PDF File (.pdf), Text File (.txt) or read online for free. H - Help Screen Orthoclase, common alkali feldspar mineral, a potassium aluminosilicate (KAlSi 3 O 8 ); it usually occurs as variously coloured, frequently twinned crystals in granite. Antero, Chaee Co.; at Crystal Pass, Goodsprings, F - Fit to Screen Original Rockhounds Discussion Group cleavage angle. An important rock-forming mineral, orthoclase is the potassium-bearing end member of the potassium sodium feldspar solid-solution series. The R.I. for light vibrating parallel to x, y and z are (, ( and (Thus ( has the lowest R.I., ( the highest, and ( intermediate. Cite this article as: Geology Science. Location: Khibiny Massif, Kola Peninsula, Russia. Ask-A-Mineralogist from the Mineralogical Society of America 6 - Orthoclase : Luminescence: Non-fluorescent. Other, rare, related feldspar varieties include adularia and anorthoclase. Only constrained solid answer happens bet Cleavages intersect at 90. Optical Properties of Orthoclase : Gladstone-Dale: CI meas= 0.011 (Superior) - where the CI = (1-KPDmeas/KC) CI calc= 0.007 (Superior) - where the CI = (1-KPDcalc/KC) KPDcalc= 0.2044,KPDmeas= 0.2036,KC= 0.2058 Ncalc = 1.52 - 1.53 : Optical Data: Biaxial (-), a=1.518, b=1.522, g=1.523-1.524, bire=0.0050-0.0060, 2V(Calc)=52-70, 2V(Meas)=65-75. Refractive Index : 1.518 - 1.530 . may not work well with some computers. Keyboard Scale: 5.2x4.6x2.2 cm. We describe their optical properties in terms of 3 perpendicular directions (x, y, z) Fig. printWin.document.close(); html += '\n\n\n'; var printReadyElem = document.getElementById("printReady"); function printSpecial() Solid answers between K-feldspar and albite are referred to as alkali feldspar. Bavaria, Carlsbad, Bohemia, and Manebach, Thuringia, Germany. A - Atoms On/Off yellow, white, pink. From the Greek orthos - "right" and kalo -" I cleave" in allusion to the mineral's right angle of good cleavage. Typically, the pure potassium endmember of orthoclase forms a solid solution with albite, the sodium endmember (NaAlSi3O8), of plagioclase. Espaol Colorless, Greenish, Grayish yellow, White, Pink. Crystalline orthoclase can also be white, colorless, cream, pale yellow, or brownish red. Dbl Clk - Start-Stop Rotation drag2 - RMB Resize/Rotate Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references. if (printReadyElem != null) At 400 degrees C or less, microcline is the stable Most minerals are biaxial. John Veevaert, Comments: Carlsbad twinned crystal of orthoclase. Optical Properties : In thin section, orthoclase has low birefringence, moderate relief, and resemblance to quartz. I - Data Info Moonstone is a variety of orthoclase that exhibits a schiller effect. Concentration of Orthoclase per GRapi unit = 0.50 (%), Estimated Radioactivity from Orthoclase - barely detectable. printWin.print(); html += headTags[0].innerHTML; Alternate names are alkali feldspar, potassium feldspar an K-feldspar. var gAutoPrint = true; // Flag for whether or not to automatically call the print function Mouse Orthoclase crystallizes in the monoclinic crystal system. Pure orthoclase is rare some sodium is usually present in the structure. 2.55 2.63 g/cm3 (Measured) 2.563 g/cm3 (Calculated). It is used as an abrasive in scouring powders and polishing compounds. Feldspar, any of a group of aluminosilicate minerals that contain calcium, sodium, or potassium. It is a type of potassium feldspar, also known as K-feldspar. Rockhounds Discussion Group on Yahoo Groups It has a hardness of 6, a specific gravity of 2.56-2.58, and a vitreous to pearly luster. Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube. Orthoclase is a common constituent of most granites and other felsic igneous rocks and often forms huge crystals and masses in pegmatite. series with celsian. } Its chemistry and atomic arrangement are variable, so optical properties vary as well. Former Martn Oliete Fontela collection. (Sverdlovsk), Ural Mountains. Gotthard, Ticino, and at Val Giuv, Tavetsch, Graubunden, Switzerland. The three principle varieties of K-feldspar are microcline (low temperature), orthoclase (medium temperature), sanidine (high temperature). In cavities in basalts; in high-grade metamorphic rocks and as a result of potassic hydrothermal alteration; also authigenic and detrital. Cleavages intersect at 90. Orthoclase (endmember formula K Al Si 3 O 8) is an important tectosilicate mineral which furms igneous rock. Comments: Striated, dark violet crystal of lorenzenite in cream-colored orthoclase. Orthoclase forms at intermediate temperatures between the stability fields of sanidine and microcline. a = 8.625, b = 12.996, c = 7.193, Z = 4; beta = 116.016 V = 724.57 Den(Calc)= 2.55. The name is frae the Greek for "straight fracture," acause its twa cleavage planes are at richt angles tae ilk ither. In Russia, from the Mursinka-Alabashka area, near Yekaterinburg Orthoclase is named based on the Greek for "straight fracture," because its two cleavages are at right angles to each other. Optical Character: Biaxial/-Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references. Polymorphism drag1 - LMB Manipulate Structure Orthoclase is one of the most common minerals, and occurs in numerous mineral environments. It is a raw material used in the production of glass, ceramic tile, porcelain, dinnerware, bathroom fixtures, and other ceramics. Orthoclase, or orthoclase feldspar, is an important tectosilicate mineral which forms igneous rock. Orthoclase: Chao S, Hargreaves A, Taylor W (1940) The structure of orthoclase. Clark Co., Nevada. Orthoclase (KAlSi 3 O 8) is the monoclinic medium-temperature Kfeldspar. if (document.getElementsByTagName != null) Has perfect cleavage on {001} and Orthoclase appears as well-formed, short, prismatic crystals, which are frequently twinned. tourmaline). Mineral Discussion Forum from Fabre Minerals - also available in if (document.getElementById != null) Drag1 - Manipulate Crystal They are almost identical in physical properties, and it is sometimes impossible to distinguish one another without x-ray analysis. - Start-Stop Rotation An adularescent gem material known as moonstone is an intergrowth of orthoclase and albite. [online] Available at: https://geologyscience.com/minerals/orthoclase/ [14th December 2020 ], Economically Important Metal Concentrations in Earths Crust, Porphyry Deposits: General characteristics and modeling, https://geologyscience.com/minerals/orthoclase/, Colorless, greenish, greyish Occurrence: Found in granite, granodiorite, syenite, and other felsic rocks. The common feldspar of granites, granite pegmatites, and syenites. Scale: Crystal size 3 x 2 cm. However, it has negative relief, is biaxial, and is often clouded by fine-grained alteration. England. { Blocky - Crystal shape tends to be equant (e.g. { Dispersion relatively strong. Keyboard (2020). It is an important ingredient of all acidic (granite, granodiorite) to neutral (syenite) igneous rocks (Table 4.1). Transparency : transparent .