Petrology

71問 • 1年前

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Mineral-like substances which are amorphous ( do not demonstrate crystallinity) or organic in origin Examples: Obsidian and Pearl

Mineraloids

Voids/ holes in the rock

Vesicle

Filled in vesicles

Amygdule

Early forming, relatively large and usually consipcous crystal distinctly larger that the grains of the rock groudmass of an igneous rock

Phenocryst

Magma produced directly from partial melting

Primary Magma

Magma that underwent minimum differentiation

Primitive Magma

Least differentiated magma in a series leading to evolved rocks

Parental Magma

Incorpotation of chemical constituents from walls or roof of the magma chamber into the magma itself

Assimilation

Piece of rock within an igneous rock that is not derived from the original magma but has been introduced from elsewhere, especially the surrounding country rock

Xenolith

Rocks are composed totally of crystals

Holocrystalline

Rock composed of a mixture of crystals and glass

Hypocrystalline

Rock consist entirely of glass

Holohyaline

Most of the minerals in the rock are euhedral

Panidiomorphic

Most of the minerals in the rock are subhedral

Hypidiomorphic

most of the minerals in the rock are anhedral

Allotriomorphic

minerals in the rock are all approximately the same shape

Equigranular

Based on quartz, alkali feldspar, pagioclase and feldspatpid content of the rock, mafic content ____

<90%

Quartzolite

>90% Quartz

Quartz-ruch Granite Rock/ Quartz-rich Granitoid/ Greisen: _____

60-90% Quartz

Alkali feldspar Grainite Granite Granodiorite Tinalita

20-60% Quartz

Orthoclase syenite syenite Monzonite Monzodiorite Anorthosite

<5% Quartz

Based on clinixpyrite,olivine and orthopyroxene content and magma is ___

Ultramafic

Based on clinopyroxene, anorthosite, and orthopyroxene content, and magma is ____

Mafic

Original/ parent rock before it metamorphosed

Protoliths

Rich in Al, K and Si

Shales/ Pelitic Rocks

Rich in Al, K, Si and Na

Quartzo-feldspathic Rocks

Fe,Mg, and Ca rich

Mafic Rocks

Mg, Fe Ni and Cr rich

Ultramafic Rocks

Rich in Ca Mg and CO2

Carbonates

Counterpart of phenocryst for metamorphic rocks

Porphyroblast

general term for describing relative T and P conditions under which metamorphic rocks form

Metamorphic Grade

Refers to change in a rock that accompany such increasing metamorphic grade

Prograde

Decreasing grade as a body of rock cools and recovers from a metamorphic or igneous event

Retrograde

Transformation of one rock type to another in the solid state

Metamorphism

Crushing and breaking of grains in rocks

Cataclasis

Reorganization of crystal lattices and inter-grain relationships through ion migration and lattice deformagion

Recrystallization

Process which resukgs in the formation of new minerals which previuosly did not exist in the metamorphic rocks

Neocrystalization

Slate, Phyllite, Schist, Gneiss, Migmatite

Foliated

Composition: Tiny chlorite and mica flakes Distinguishing features: slaty cleavage, Smooth dull surface

Slate

Disntinguishing features: fine-grained, glossy sheen ( phyllitic sheen caused by tiny quartz and mica ) and breaks along wavy surfaces

Phyllite

Compostion: micas dominate Distinguishing features: medium- coarse grained rock with scaly foliation (schistosity)

Schist

Dinstinguishing features: coarse grained, compositional banding( gneissic banding) due to segregation of light and dark colored minerals

Gneiss

Formed by remaining mafic minerals when gneiss is further heated and felsic minerals start to melt and the solidify again afterwards, creating more distinct layers of felsic and mafic minerals

Migmatite

Mylonite, Metaconglomerate

Weakly Foliated

Composition: intensely flattered minerals in a fine grained streaked matrix Formed in by ductile deformation during intense shearing encountered during folding and faulting

Mylonite

Stretched pebbles with preffered orientation

Metaclongomerate

Marble, Quartzite, Hornfels, Anthracite, fault Breccia, Cataclasite, Impact Breccia, Tektites

Non Foliated

Composition: interlocking medium-coarse calcite or dolomite grauns

Quartzite

Usually dark, fine-grained massive rock with dull luster

Hornfels

Fine grained, shiny black rock that may exhibit conchoidal fracture Metamorphosed coal

Anthracite

Rock made up of broken frgaments in a haphazard arrangement

Fault Breccia

Forms from the pulverized and shattered rock generated by impact metamorphism

Impact Breccia

Silica rich glass beads formed from the melting of crustal rock during impact metamorphism

Tektites

Rocks derived from pre existing materials and produced through physical, chemical and biological processes on earths surface

Sedimentary Rocks

Limestone, Chert, Coal

Biogenic/ Biochemical

Weathering, Erioson/Transportation, Deposition/Precipitation, Compaction/Diagenetic Processes

Sedimentary Processes

Usual products: Quartz sand, clay or calcite

Weathering

Transport of weathered rock by gravity, wind, water or ice

Erosion/Transportation

Occurs when water velocity decreases

Deposition/Precipitation

Refers to physical and chemical changes which take place after the deposition of sediments

Diagenesis

Produced when there is a change in pattern of deposition- sediments composition and/or grain size

Bedding/Lamination

Bedding planes created when laminae and beds are deposited in repetitive cycles, typically daily or seasonally

Varves

Sandstone which is 0-15% matrix

Arenites

Sandstone which is 15-75% matrix

Wackes

Sandstones which is 75-100 % matrix

Mudstones

Sandstone which is >50% calcareous sediment

Calcerenites

Classic sedimentary rock that is composed mostly of silt

Silstone/Aleurolite

Fine-grained, dark gray sedimentary rock, which is formed from silt and clay

Mudstone

fine-grained, dark gray to pink sedimentary rock which mainly consists of compacted and hardened clay

Claystone

Clay stone with fissility

Shake

Mictric, Oolitic, Bioclastic

Limestone

Mineral Processing

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Mineral Processing