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Monzonite Nicol Paralleli
Monzonite is an igneous intrusive rock, formed by slow cooling of underground magma that has a moderate silica content and is enriched in alkali metal oxides. Monzonite is composed mostly of plagioclase and alkali feldspar. Syenodiorite is an obsolescent term for monzonite or for monzodiorite.Le Maitre, R.W., ''Igneous Rocks: A Classification and Glossary of Terms'' Cambridge University Press, 2nd ed, pp. 113 Larvikite is a particular form of monzonite. Description Monzonite is a coarse-grained (phaneritic) igneous rock. Such rocks are classified by their relative percentages of quartz, plagioclase, alkali feldspar, and feldspathoid (the QAPF classification). Monzonite is defined as rock having less than 5% quartz in its QAPF fraction and in which alkali feldspar makes up between 35% and 65% of the total feldspar content. If quartz constitutes greater than 5% of the QAPF fraction, the rock is termed a quartz monzonite, while if feldspathoids are present as up to 10% of the Q ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plagioclase
Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more properly known as the plagioclase feldspar series. This was first shown by the German mineralogist Johann Friedrich Christian Hessel (1796–1872) in 1826. The series ranges from albite to anorthite endmembers (with respective compositions NaAlSi3O8 to CaAl2Si2O8), where sodium and calcium atoms can substitute for each other in the mineral's crystal lattice structure. Plagioclase in hand samples is often identified by its polysynthetic crystal twinning or 'record-groove' effect. Plagioclase is a major constituent mineral in the Earth's crust, and is consequently an important diagnostic tool in petrology for identifying the composition, origin and evolution of igneous rocks. Plagioclase is also a major constituent of rock in the highlan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
QAPF Classification
A QAPF diagram is a double ternary diagram which is used to classify igneous rocks based on mineralogic composition. The acronym QAPF stands for "Quartz, Alkali feldspar, Plagioclase, Feldspathoid (Foid)". These are the mineral groups used for classification in QAPF diagram. Q, A, P and F percentages are normalized (recalculated so that their sum is 100%). Origin QAPF diagrams were created by the International Union of Geological Sciences (IUGS): ''Subcommission on the Systematics of Igneous Rocks'' fostered by Albert Streckeisen (whence their alternative name: Streckeisen diagrams). Geologists worldwide accept the diagrams as a classification of igneous, especially plutonic rocks. Usage QAPF diagrams are mostly used to classify plutonic rocks (phaneritic rocks), but are also used to classify volcanic rocks if modal mineralogical compositions have been determined. QAPF diagrams are not used to classify pyroclastic rocks or volcanic rocks if modal mineralogical composition is n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Granodiorite
Granodiorite () is a coarse-grained (phaneritic) intrusive igneous rock similar to granite, but containing more plagioclase feldspar than orthoclase feldspar. The term banatite is sometimes used informally for various rocks ranging from granite to diorite, including granodiorite. Composition According to the QAPF diagram, granodiorite has a greater than 20% quartz by volume, and between 65% and 90% of the feldspar is plagioclase. A greater amount of plagioclase would designate the rock as tonalite. Granodiorite is felsic to intermediate in composition. It is the intrusive igneous equivalent of the extrusive igneous dacite. It contains a large amount of sodium (Na) and calcium (Ca) rich plagioclase, potassium feldspar, quartz, and minor amounts of muscovite mica as the lighter colored mineral components. Biotite and amphiboles often in the form of hornblende are more abundant in granodiorite than in granite, giving it a more distinct two-toned or overall darker appearan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gabbro
Gabbro () is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is chemically equivalent to rapid-cooling, fine-grained basalt. Much of the Earth's oceanic crust is made of gabbro, formed at mid-ocean ridges. Gabbro is also found as plutons associated with continental volcanism. Due to its variant nature, the term ''gabbro'' may be applied loosely to a wide range of intrusive rocks, many of which are merely "gabbroic". By rough analogy, gabbro is to basalt as granite is to rhyolite. Etymology The term "gabbro" was used in the 1760s to name a set of rock types that were found in the ophiolites of the Apennine Mountains in Italy. It was named after Gabbro, a hamlet near Rosignano Marittimo in Tuscany. Then, in 1809, the German geologist Christian Leopold von Buch used the term more restrictively in his descri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biotite
Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula . It is primarily a solid-solution series between the iron-endmember annite, and the magnesium-endmember phlogopite; more aluminous end-members include siderophyllite and eastonite. Biotite was regarded as a mineral ''species'' by the International Mineralogical Association until 1998, when its status was changed to a mineral ''group''. The term ''biotite'' is still used to describe unanalysed dark micas in the field. Biotite was named by J.F.L. Hausmann in 1847 in honor of the French physicist Jean-Baptiste Biot, who performed early research into the many optical properties of mica. Members of the biotite group are sheet silicates. Iron, magnesium, aluminium, silicon, oxygen, and hydrogen form sheets that are weakly bound together by potassium ions. The term "iron mica" is sometimes used for iron-rich biotite, but the term also refers to a flaky micaceous form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hornblende
Hornblende is a complex inosilicate series of minerals. It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende minerals are common in igneous and metamorphic rocks. The general formula is . Physical properties Hornblende has a hardness of 5–6, a specific gravity of 3.0 to 3.6, and is typically an opaque green, dark green, brown, or black color. It tends to form slender prismatic to bladed crystals, diamond-shaped in cross-section, or is present as irregular grains or fibrous masses. Its planes of cleavage intersect at 56° and 124° angles. Hornblende is most often confused with the pyroxene series and biotite mica, which are also dark minerals found in granite and charnockite. Pyroxenes differ in their cleavage planes, which intersect at 87° and 93°. Hornblende is an inosilicate (chain silicate) mineral, built around double chains of silica tetrahedra. These chains extend the length of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthoclase
Orthoclase, or orthoclase feldspar (endmember formula K Al Si3 O8), is an important tectosilicate mineral which forms igneous rock. The name is from the Ancient Greek for "straight fracture," because its two cleavage planes are at right angles to each other. It is a type of potassium feldspar, also known as K-feldspar. The gem known as moonstone (see below) is largely composed of orthoclase. Formation and subtypes Orthoclase is a common constituent of most granites and other felsic igneous rocks and often forms huge crystals and masses in pegmatite. Typically, the pure potassium endmember of orthoclase forms a solid solution with albite, the sodium endmember (NaAlSi3O8), of plagioclase. While slowly cooling within the earth, sodium-rich albite lamellae form by exsolution, enriching the remaining orthoclase with potassium. The resulting intergrowth of the two feldspars is called perthite. The higher-temperature polymorph of KAlSi3O8 is sanidine. Sanidine is common in rapidly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euhedral
Euhedral crystals (also known as idiomorphic or automorphic crystals) are those that are well-formed, with sharp, easily recognised faces. The opposite is anhedral (also known as ''xenomorphic'' or ''allotriomorphic''): a rock with an anhedral texture is composed of mineral grains that have no well-formed crystal faces or cross-section shape in thin section. Anhedral crystal growth occurs in a competitive environment with no free space for the formation of crystal faces. An intermediate texture with some crystal face-formation is termed subhedral. Crystals that grow from cooling liquid magma typically do not form smooth faces or sharp crystal outlines. As magma cools, the crystals grow and eventually touch each other, preventing crystal faces from forming properly or at all. When snowflakes crystallize, they do not touch each other. Thus, snowflakes form euhedral, six-sided twinned crystals. In rocks, the presence of euhedral crystals may signify that they formed early in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subhedral
Euhedral crystals (also known as idiomorphic or automorphic crystals) are those that are well-formed, with sharp, easily recognised faces. The opposite is anhedral (also known as ''xenomorphic'' or ''allotriomorphic''): a rock with an anhedral texture is composed of mineral grains that have no well-formed crystal faces or cross-section shape in thin section. Anhedral crystal growth occurs in a competitive environment with no free space for the formation of crystal faces. An intermediate texture with some crystal face-formation is termed subhedral. Crystals that grow from cooling liquid magma typically do not form smooth faces or sharp crystal outlines. As magma cools, the crystals grow and eventually touch each other, preventing crystal faces from forming properly or at all. When snowflakes crystallize, they do not touch each other. Thus, snowflakes form euhedral, six-sided twinned crystals. In rocks, the presence of euhedral crystals may signify that they formed early in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andesine
Andesine is a silicate mineral, a member of the plagioclase feldspar solid solution series. Its chemical formula is ( Ca, Na)( Al, Si)4 O8, where Ca/(Ca + Na) (% anorthite) is between 30–50%. The formula may be written as Na0.7-0.5Ca0.3-0.5Al1.3-1.5Si2.7-2.5O8. The plagioclase feldspars are a continuous solid solution series and as such the accurate identification of individual members requires detailed optical study, chemical analysis or density measurements. Refractive indices and specific gravity increase directly with calcium content.Klein, Cornelis, and Cornelius S. Hurlbut, Jr., ''Manual of Mineralogy,'' Wiley, 20th ed. 1985, p. 455 It is sometimes used as a gemstone. Name and discovery Andesine was first described in 1841 for an occurrence in the Marmato mine, Marmato, Cauca, Chocó Department, Colombia. The name is for the Andes due to its abundance in the andesite lavas in those mountains. In the early 2000s, red and green gemstones began to be marketed under the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligoclase
Oligoclase is a rock-forming mineral belonging to the plagioclase feldspars. In chemical composition and in its crystallographic and physical characters it is intermediate between albite ( Na Al Si3 O8) and anorthite ( CaAl2Si2O8). The albite:anorthite molar ratio of oligoclase ranges from 90:10 to 70:30. Oligoclase is a high sodium feldspar crystallizing in the triclinic system. The Mohs hardness is 6 to 6.5 and the specific gravity is 2.64 to 2.66. The refractive indices are: nα=1.533–1.543, nβ=1.537–1.548, and nγ=1.542–1.552. In color it is usually white, with shades of grey, green, or red. Oligoclase is a common mineral in the more silica-rich varieties of igneous rock and in many metamorphic rocks. Name and discovery The name oligoclase was given by August Breithaupt in 1826 from the grc, όλίγος, oligos, little, and grc, κλᾶν, klân, to break, because the mineral was thought to have a less perfect cleavage than albite. It had previously been recognize ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latite
Latite is an igneous, volcanic rock, with aphanitic- aphyric to aphyric-porphyritic texture. Its mineral assemblage is usually alkali feldspar and plagioclase in approximately equal amounts. Quartz is less than five percent and is absent in a feldspathoid-bearing latite, and olivine is absent in a quartz-bearing latite. When quartz content is greater than five percent the rock is classified as quartz latite.Classification of Igneous Rocks , , and scar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
