Classification of Igneous Rocks - Mine Engineer.Com
Porphyritic Texture - contains both coarse and fine crystaline structures. Glassy Texture - extremely smooth, like glass, cools extremely fast on the surface. Fragmental Texture - fragments, which results from an exploding volcano. As Magma becomes Lava, temperature decreases and the pressure decreases.
Pegmatite: Igneous Rock - Pictures, Definition & More
The mining of pegmatites might be done in an underground operation that follows a dike or exploits a small pocket. It can also be done at an outcrop where the pegmatite is easily discovered by people. Pegmatites usually do not support large mining operations that employ dozens of workers and have continuous activity of many years.
Major Mines & Projects | Aitik Mine - Mining Intelligence and
Both rock types show porphyritic texture, the former having amphibole phenocrysts while the latter is plagiophyric. The rocks within the ore zone transition from biotite gneiss, to biotite schist, to muscovite schist towards the hanging wall.
Porphyritic | Definition of Porphyritic by Merriam-Webster
Porphyritic definition is - of or relating to porphyry.
Chapter 3: Igneous Textures
Chapter 3: Igneous Textures • Magmatic reaction and resorption – Fig. 3.10 is an example – Olivine OPX – Resorption – refusion or dissolution of mineral back into the melt or solution from which it formed – Resorbed crystals commonly have rounded corners or are embayed – Sieve texture (Fig. 3.11a) – evidence for advanced
Geology Fundamentals: Identifying Igneous Rocks in the
Oct 17, 2019 · These rocks exhibit intermediate grain size and often a porphyritic texture. Magmas emplaced near the surface cool relatively quickly, hence hypabyssal rocks are believed to be the transitional rocks between the intrusive and extrusive.
Igneous Rocks: Formation Texture and Composition | Geology
This texture showing large sized crystals within a matrix of small crystals is the porphyritic texture. The large crystals, because of their prominence in the rock are called phenocrysts. Phenocrysts may have sharp edges and well-formed crystal faces or they may be corroded and somewhat irregular. iv. Pegmatite Texture: This rock is an intrusive rock.
PDF ROCKS and how to identify them.ppt - University of Arizona
Porphyritic mica feldspar Granite - intrusive Pegmatite a Special Case tourmaline feldspar mica quartz PEGMATITES are classified as intrusive igneous rocks, but there is a difference. They are VERY coarse grained and strictly speaking are not crystallizing out of a magma. The coarse grained nature is the result of crystal growth in
Porphyry | geological feature | Britannica
Porphyry. Rocks have many different textures. Layered sandstone produces a gritty texture, whereas coquina may be rough with cemented shells occasionally producing a sharp edge. Likewise, breccia, which contains pieces of other rocks that have been cemented together, and porphyry, which contains interlocking mineral crystals, tend to be rough.
Porphyritic - Find link
This porphyritic texture is indicative of multi-stage cooling of magma. For example, porphyritic andesite will have large phenocrysts Geology of Macau (159 words) [view diff] exact match in snippet view article find links to article
Igneous rocks - slideshare.net
Feb 25, 2017 · Granite is a felsic intrusive igneous rock and has either a phaneritic or porphyritic texture. Granite cools very slowly and often forms large masses of rock that are referred to as plutons or batholiths. Granite usually contains about 20-50% quartz, 30-60% feldspar, and the remaining 5-10% darker minerals such as biotite. The quartz grains are usually spherical in shape and are a white to …
Porphyritic texture - ALEX STREKEISEN
Porphyritic texture Porphyritic texture is an igneous rock texture in which large crystals are set in a finer-grained or glassy groundmass. Porphyritic textures occur in coarse, medium and fine-grained igneous rocks. Usually the larger crystals, known as phenocrysts, …
Porphyritic | Definition of Porphyritic at Dictionary.com
Porphyritic definition, of, pertaining to, containing, or resembling porphyry, its texture, or its structure. See more.
Porphyritic granite: Mineral information, data and localities
A granite exhibiting porphyritic texture. Essential minerals - these are minerals that are required within the classification of this rock:
GOLD, COPPER & GEMSTONES in ARIZONA: GOLD in ARIZONA - a
This texture is a rock fabric in which large crystals (such as feldspar and quartz) are dispersed throughout a finer grained matrix in an igneous rock as a result of slow cooling in a magma chamber at relatively shallow depth. Underground at the Resolution mine, Superior, AZ The author with friend Rich at the Resolution shaft, Arizona
Granite (porphyritic) - Department of Earth Sciences
The most striking feature of its texture is the large pink angular potassium feldspar crystals (one of which is indicated by the yellow pointer). This texture, of large well-formed crystals in a finer matrix, is called porphyritic. It indicates that some crystals formed early in the magma, and had quite a long time to grow large before the ...
Porphyritic texture in granite - Stock Image - E417/0295
Porphyritic texture in granite rock. Granite is a dark grey igneous rock, formed when volcanic magma solidifies under pressure in the Earth's crust. This granite is porphyritic, containing large, isolated, pink crystals of feldspar. Feldspar is the most common mineral in the crust. This sample measures 120 millimetres across.
Definition of porphyritic
Definition of porphyritic i. Said of the texture of an igneous rock in which larger crystals ( phenocryst s) are set in a finer-grained groundmass, which may be crystalline or glassy or both.
Mafic - Mining Fundamentals
Basalt can also be observed with a porphyritic texture, which undergoes partial crystallization at depth, and an eruption at the surface. The composition of gabbro is typically the same as that of basalt. However, gabbro has a different texture, with larger crystals formed deep inside the Earth's surface.
Granite - BHM Granite & Marble South Africa
A granitic rock with a porphyritic texture is known as a granite porphyry. Granitoid is a general, descriptive field term for lighter-colored, coarse-grained igneous rocks. Petrographic examination is required for identification of specific types of granitoids. The extrusive igneous rock equivalent of …
what is porphyritic texture? | Yahoo Answers
Porphyry now refers to a texture of igneous rocks. Its chief characteristic is a large difference between the size of the tiny matrix crystals and other much larger crystals, called phenocrysts.
Porphyritic texture in an igneous rock - Stock Image
Porphyritic texture in an igneous rock. The large, isolated crystals consist of the feldspar mineral labradorite. These are held within dark, fine- grained igneous rock, or rock that has solidified from molten magma. This pattern of large mineral crystals within a matrix is known as porphyritic texture. This sample measures 100 millimetres across.
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Lamprophyre - Mining Fundamentals
Automotive Innovation in the Mining Industry Lamprophyre is characterized by a porphyritic texture, in which phenocrysts are enclosed in a fine- grained to dense groundmass. The groundmass consists of perovskite, Fe-Ti oxides, glass, pyroxene, amphibole, mica, melilite, monticellite, carbonate, feldspathoids, alkali feldspar, and plagioclase.
Origin of Mesozoic Porphyritic Rocks and Regional Magmatic
Abstract: Mesozoic porphyritic rocks from the Zijinshan area, southwestern Fujian Province, China, are andesitic to rhyolitic in composition. The whole-rock SiO 2 contents of these rocks are between 62.5% and 78.1%. Magmatic zircon from the Mesozoic porphyritic rocks was determined
PDF What is a Porphyry Copper Deposit?
The term "porphyry copper" is derived from the texture of the igneous rock that forms these intrusive bodies. Porphyritic texture is characterized by larger crystals of feldspar and quartz, known as phenocrysts, which are surrounded by a matrix of very fine-grained crystals.
Porphyritic - Wikipedia
Porphyritic texture in a granite. This is an intrusive porphyritic rock. The white, square feldspar phenocrysts are much larger than crystals in the surrounding matrix; eastern Sierra Nevada, Rock Creek Canyon, California.
Porphyry (geology) - Wikipedia
The term porphyry is also used for a mineral deposit called a "copper porphyry". The different stages of cooling that create porphyritic textures in intrusive and hypabyssal porphyritic rocks also lead to a separation of dissolved metals into distinct zones.. This process, which occurs primarily when fluids are driven off the cooling magma, is one of the main reasons for the existence in the ...
Porphyry copper deposit - Wikipedia
Porphyry copper deposits are copper ore bodies that are formed from hydrothermal fluids that originate from a voluminous magma chamber several kilometers below the deposit itself. Predating or associated with those fluids are vertical dikes of porphyritic intrusive rocks from which this deposit type derives its name. In later stages, circulating meteoric fluids may interact with the magmatic ...
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What is porphyritic andesite?
Porphyritic textures develop when conditions during cooling of a magma change relatively quickly. The earlier formed minerals will have formed slowly and remain as large crystals, whereas, sudden cooling causes the rapid crystallization of the remainder of the melt into a fine grained (aphanitic) matrix.
Porphyry Copper Deposits | Geology for Investors
This porphyritic rock has large feldspar crystals in a finer grained matrix. Today a porphyry is, if it's talked about at all, associated with large-scale mining. However, not all porphyries are mineralised; it is a general term to describe an igneous rock that has some large-grained crystals ("phenocrysts") within a fine-grained matrix.
Granite (porphyritic) - University of Oxford
Granite (porphyritic); Shap, Cumbria In terms of its mineral content this is a typical granite, consisting of pink potassium feldspar, cream sodium feldspar (plagioclase), grey quartz and black biotite mica. The most striking feature of its texture is the large pink angular potassium feldspar crystals (one of which is indicated by the yellow ...
The Anatomy of an Alkalic Porphyry Cu-Au System: Geology
The Late Ordovician-early Silurian (~455–435 Ma) Northparkes system is a group of silica-saturated, alkalic porphyry deposits and prospects that developed within the Macquarie island arc. The system is host to a spectacular and diverse range of rocks and alteration-mineralization textures that facilitate a detailed understanding of its evolution, in particular the nature and controls of porphyry-related …
Porphyritic - definition of porphyritic by The Free Dictionary
Define porphyritic. porphyritic synonyms, porphyritic pronunciation, porphyritic translation, English dictionary definition of porphyritic. also por·phy·rit·i·cal adj. 1. Of or containing porphyry.
Rock Textures - Geology for Today - Dr. Tambra L. Eifert
Porphyritic texture is represented by igneous rocks which have minerals grains of different sizes. The larger minerals are called phenocrysts. The smaller ones are collectively known as groundmass, which is simply the grains between the phenocrysts. The groundmass can be aphanitic or phaneritic; therefore, the only requirement for this type of ...
Porphyritic | Definition of Porphyritic by Oxford Dictionary
‘The original porphyritic texture with plagioclase phenocrysts is still recognizable.’ ‘It is a light grey, porphyritic volcanic to subvolcanic rock, which shows almost no deformation.’ ‘The biotite-granite continues these trends of increasing orthoclase over plagioclase and biotite over homblende, to produce a coarse-grained pink ...
Porphyry may refer to: Porphyritic, the general igneous text
Porphyry may refer to: Porphyritic, the general igneous texture of a rock with two distinct crystal phenocryst sizes Porphyry geology, an igneous rock with large crystals in a fine-grained matrix and important Roman building material Porphyry Mountain in Alaska Porphyry, a system of astrological house division Porphyry copper deposit, a primary low grade ore deposit of copper, consisting of ...
Coarse-Grained Porphyritic Textures
A porphyritic texture displays minerals in two distinct size populations: one or more minerals are consistently larger than the rest of the minerals in a rock. The extra large mineral grains are called phenocrysts. Feldspars, augite, and hornblende commonly show rectangular crystal shapes, whereas ...
Porphyritic Textures with Fine-Grained Groundmasses
Many rocks with an overall fine-grained texture display scattered minerals that are more than 1 mm across. This porphyritic texture indicates that the magma sat and cooled a bit below the Earth's surface, thus giving time for the large crystals to grow, before …