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Oligoclase - Wikipedia, the free encyclopedia Oligoclase is a rock-forming mineral belonging to the plagioclase feldspars. Oligoclase occurs, often accompanying orthoclase, as a constituent of plutonic igneous rocks such as granite, syenite, and diorite. The distinctive texture of rapakivi granite is due to oligoclase rims on orthoclase phenocrysts. en.wikipedia.org /?title=Oligoclase   (366 words)

Encyclopedia: Oligoclase   (Site not responding. Last check: 2007-11-04) OLIGOCLASE, a rock-forming mineral belonging to the plagioclase (q.v.) division of the felspars. Oligoclase is common in granite, syenite, diorite and gneiss. The name oligoclase is derived from the Greek for little and fracture, in reference to the fact that its cleavage angle differs significantly from 90°. www.nationmaster.com /encyclopedia/Oligoclase   (1207 words)

OLIGOCLASE - LoveToKnow Article on OLIGOCLASE   (Site not responding. Last check: 2007-11-04) The name oligoclase was given by A. Breithaupt in 1826 from the Gr. Norway; this presents a brilliant red metallic glitter, due to the presence of numerous small scales of haematite or gthite enclosed in the felspar. Oligoclase occurs, often accompanying orthoclase, as a constituent of igneous rocks of various kinds; for instance, amongst plutonic rocks in granite, syenite, diorite; amongst dike-rocks in porphyry and diabase; and amongst volcanic rocks in andesite and trachyte. www.1911encyclopedia.org /O/OL/OLIGOCLASE.htm   (315 words)

* Oligoclase - (Jewelry): Definition Oligoclase is not a well known mineral but has been used as semi-precious stone under the names of sunstone and moonstone. Oligoclase occurs as massive specimens and is a common mineral in the surrounding country rock. Sunstone is a species of feldspar called "oligoclase" or known sometimes in the jewelry industry as "adventurine feldspar". en.mimi.hu /jewelry/oligoclase.html   (304 words)

Lord Hill Pegmatite, Stoneham Maine The probable explanation of the myrmekite is that after the consolidation of the diorite, calcium was introduced into it and calcic plagioclase formed by replacement of oligoclase. The myrmekitic andesine to bytownite of the diorite was reacted upon by the pegmatite magma to produce oligoclase which retained the original myrmekitic quartz intergrowths. Oligoclase (in part) and biotite are earlier in origin and, as previously stated, are believed to have been derived from the diorite wall rock. www.minsocam.org /msa/collectors_corner/arc/melordpeg.htm   (5085 words)

CT DEP: Bedrock Geology Detailed Data Guide Support   (Site not responding. Last check: 2007-11-04) Gray to silvery, non-rusty, medium-grained, well-layered alternating schist and granofels, composed of quartz, oligoclase, muscovite, biotite, and garnet, commonly with staurolite and kyanite (or sillimanite); schist commonly graphitic Chiefly gray, medium-grained, well-layered granofels, composed of quartz, oligoclase, and biotite, commonly with garnet and sillimanite, interlayered with thinly fissile sillimanitic, graphitic, pyrrhotitic biotite schist and with calc-silicate rock Gray, rusty-weathering, medium- to coarse-grained, interlayered schist and gneiss, composed of oligoclase, quartz, K-feldspar, and biotite, and commonly garnet, sillimanite, graphite, and pyrrhotite. dep.state.ct.us /gis/dataguides/dep/layers/support/bedrock/detailed.htm   (4714 words)

Crystals O - Spiritual Platform   (Site not responding. Last check: 2007-11-04) OLIGOCLASE Oligoclase is a great stone to choose if you are dealing with issues of trust; it assists one in learning trust. Oligoclase also allows one stability and focus to see the highest perspective or vision, the creative intelligence and wisdom, without loosing sight of the detail or what needed to happen to achieve it. Oligoclase is a mineral species in the plagioclase series of the feldspar group. www.spiritualplatform.org /sp/crystals/crystalso.html   (1192 words)

[No title] The Askore Amphibolite consists of medium-grade banded intermediate meta-volcanics with hornblende, oligoclase, biotite, epidote, minor quartz, rutile and sporadic muscovite and garnet. The igneous clinopyroxene is rimmed by coronas of garnet (Alm Omphacite (Jd) is mainly preserved as inclusions in kyanite and epidote, being elsewhere replaced by a symplectite of magnesio- to actinolitic hornblende + quartz ±; oligoclase. www.personalweb.unito.it /franco.rolfo/1998rolfo.htm   (2372 words)

OLIGOCLASE (Sodium Calcium Aluminum Silicate) Oligoclase is a member of the Plagioclase Feldspar Group. Oligoclase by definition must contain 90-70% sodium to 10-30% calcium in the sodium/calcium position of the crystal structure. Oligoclase can be found as a major rock forming component in granites and syenites. mineral.galleries.com /minerals/silicate/oligocla/oligocla.htm   (446 words)

OLIGOCLASE : Another Rare Gemstone From Lapilia.com   (Site not responding. Last check: 2007-11-04) Oligoclase is a member of the plagioclase series of feldspars. faceted oligoclase gems, and all are very pale in color if not colorless. The following gemstones might be confused with oligoclase: petalite, magnesite, orthoclase, albite and apophyllite. www.lapilia.com /2oligocl.htm   (66 words)

The plagioclase feldspar oligoclase Oligoclase is industrially important in the manufacture of ceramics. Quality Oligoclase crystals are reported from a quarry in St. Lawrence Co., New York. Moonstone Oligoclase is found along many North American beaches in the form of naturally rounded pebbles. www.minerals.net /mineral/silicate/tecto/feldspar/oligocla.htm   (246 words)

Oligoclase   (Site not responding. Last check: 2007-11-04) '''Oligoclase''' is a rock-forming mineral belonging to the plagioclase division of the feldspars. It is thus a sodalime feldspar crystallizing in the anorthic system. Another variety more frequently used as a gemstone is the aventurine-feldspar or sun-stone (q.v.) found as reddish cleavage masses in gneiss at Tvedestrand in southern Norway; this presents a brilliant red metallic glitter, due to the presence of numerous small scales of haematite or ?thite enclosed in the feldspar. oligoclase.iqnaut.net   (289 words)

LEUCITE - LoveToKnow Article on LEUCITE   (Site not responding. Last check: 2007-11-04) The leucite is often j5resent in two sets of crystals, both porphyritic and as an ingredient of the ground mass. The felspar ranges from bytownite to oligoclase, being tisually a variety of labradorite; orthoclase is scarce. The augite varies a good deal in character, being green, brown or violet, but aegirinc (the dark green pleochroic soda-iron-augite) is seldom present. 90.1911encyclopedia.org /L/LE/LEUCITE.htm   (1372 words)

Table T6. Brief petrographic descriptions of analyzed basalts and X-ray diffraction of secondary minerals from fine ... Olivine-clinopyroxene-plagioclase glomerophyric basalt, weakly vesicular (~2%-3%; to 0.1-0.3 mm), incompletely crystallized, with intersertal texture.Phenocrysts and microphenocrysts (30%-35%) mainly of plagioclase (labradorite oligoclase). Phenocrysts (10%) represented mainly by zoned plagioclase (central part of plagioclase of labradorite and rim-by oligoclase), sometimes plagioclase represented by accretions with olivine. Phenocrysts (30%-35%) of olivine (0.1-0.3 mm), clinopyroxene (0.1-0.6 mm), and tabular plagioclase (labradorite, oligoclase; to 0.1-0.7 mm). www-odp.tamu.edu /publications/183_SR/013/013_t6.htm   (1006 words)

Oligoclase Oligoclase is a member of the solid solution plagioclase feldspar group between albite (pure NaAlSi Oligoclase has between 70% - 90% Na and 10% - 30% Ca. Better known are two varieties of oligoclase, Sunstone and Moonstone. www.museums.udel.edu /mineral/mineral_site/collection/alphabetical/O/oligoclase.html   (73 words)

Mineral description : Oligoclase   (Site not responding. Last check: 2007-11-04) White to grayish, or pale nuances of green yellow or brown. Oligoclase is a member of the plagioclase feldspar series. Two varietys of oligoclase that's been used as precious stones are moonstone and sunstone. www.geology.neab.net /minerals/oligocla.htm   (175 words)

Rocks and Minerals (O-Z)   (Site not responding. Last check: 2007-11-04) It's name is derived from the characteristic olive green colour. It is the plagioclase feldspar group includes: albite, oligoclase, andesine, labradorite, bytownite, anorthite. It is a common accessory mineral found in all types of igneous rocks. www7.informatik.uni-erlangen.de /tree/IMMD-VII/Probert_Encyclopaedia/h3.htm   (2440 words)

Plagioclase   (Site not responding. Last check: 2007-11-04) Some albite, oligoclase, and labradorite in coarse cleavages commonly exhibit a play of colors in shades of blue or blue-green, yellow, and brown. Bytownite and labradorite are characteristic of igneous rocks of gabbroic composition and of the anorthosites; andesine, of andesites and diorites; oligoclase, of monzonites and granodiorites; albite, of granites and granitic pegmatites. Albite and oligoclase are mined from some pegmatites and used in the manufacture of ceramics and as the abrasive in toothpaste. geology.csupomona.edu /alert/mineral/plagioclase.htm   (229 words)

Sunstone - Gemstone Information   (Site not responding. Last check: 2007-11-04) Sunstone is a gem variety of oligoclase feldspar. Oligoclase is a variety of plagioclase feldspar, which is itself an isomorphous mixture of albite (sodium aluminium silicate) and anorthite (calcium aluminium silicate). In common with other feldspar gems, it displays a schiller of coloured light, caused by inclusions or its crystal structure creating interference effects of light. www.24carat.co.uk /sunstone.html   (109 words)

oligoclase - Wiktionary Primarily found as small crystals in impure marble. Oligoclase contains a small amount of calcium substituting for some of the sodium in its formula. Oligoclase with reddish-golden inclusions found in Norway and Canada is called sunstone. en.wiktionary.org /wiki/Oligoclase   (88 words)

Medinah Minerals, Inc. - Vancouver Petrographic 10.6.00 Report The creamy-coloured areas surrounding the mottles appear to be composed mainly of secondary alkali feldspar, possibly of oligoclase composition to judge by the relief against quartz, and lesser pyroxene and quartz, all forming subhedra mainly <0.2 mm in size. Clots of alteration minerals with irregular outlines up to about 1.5 mm across are composed of epidote, chlorite, apatite, carbonate and ?zeolite; relict plagioclase in some suggests they may be after former calcic plagioclase, but abundant sphene in others suggest derivation from former mafic crystals such as ?pyroxene. Negative relief of the plagioclase against quartz suggests it may be sodic (?oligoclase or albite), and in part secondary. www.medinah-minerals.com /reports/petrographic_11-6-00.html   (7362 words)

CT DEP: Bedrock Geology Metadata Ordovician) Gray, medium-grained, interlayered schist and granofels, composed of quartz, oligoclase, muscovite (in the schist), biotite, and garnet, also staurolite and kyanite in the schist. Ordovician) Gray to silver, medium- to fine-grained, well-layered to laminated schist and granofels, composed of quartz, oligoclase or albite, muscovite or sericite, biotite or chlorite, and in western belt local garnet, staurolite, and kyanite. and Middle Ordovician) Gray, rusty-weathering, medium- to coarse-grained, interlayered schist and gneiss, composed of oligoclase, quartz, K-feldspar, and biotite, and commonly garnet, sillimanite, graphite, and pyrrhotite. dep.state.ct.us /gis/dataguides/dep/layers/metadata/bedrock.htm   (5946 words)

OLIGOCLASE - Encyclopedia Britannica - OLIGOCLASE - JCSM's Study Center   (Site not responding. Last check: 2007-11-04) It is thus a soda-lime felspar crystallizing in the anorthic system. Norway; this presents a brilliant red metallic glitter, due to the presence of numerous small scales of haematite or gothite enclosed in the felspar. Oligoclase occurs, often accompanying orthoclase, as a constituent of igneous rocks of various kinds; for instance, amongst plutonic rocks in granite, jcsm.org /StudyCenter/Encyclopedia_Britannica/NUM_ORC/OLIGOCLASE.html   (692 words)

Avalon Crystals-Gemstone properties of crystals and stones. Healing and Gemological. Obsidian is wide spread throughout the world at those places where volcanic activity occurs or has occurred in the past. - Oligoclase is a great stone to choose if you are dealing with issues of trust; it assists one in learning trust. - Oligoclase is a mineral species in the plagioclase series of the feldspar group. www.neatstuff.net /avalon/info/info-o.html   (1564 words)

MSN Encarta - Search Results - oligoclase Granite, igneous rock of visible crystalline formation and texture. It is composed of feldspar (usually potash feldspar and oligoclase) and quartz,... Exclusively for MSN Encarta Premium Subscribers--quickly search thousands of articles from magazines such as Time, Newsweek, The Atlantic Monthly, and Smithsonian. ca.encarta.msn.com /oligoclase.html   (58 words)

USGS Spectroscopy Lab - Clark et. al. 2003 Spectral Library splib05a Comments: Sharp peaks show good resolution of alpha1-alpha2 components, suggesting good crystallinity and homogeneity of compositional and structural state. All other peaks were indexed following Borg and Smith (1969) for oligoclase. Line- and profile-based search-match routines return ordered oligoclase (41-1480) and disordered albite (10-0393) as the most likely hits. pubs.usgs.gov /of/2003/ofr-03-395/DESCRIPT/M/oligoclase_hs110.html   (288 words)

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