What type of metamorphism is quartzite

Today it is not very advantageous to use this rock because of its weight and the splitting and cracking over time. Schist is a medium grade metamorphic rock.

This means that it has been subjected to more heat and pressure than slate, which is a low grade metamorphic rock. As you can see in the photo above schist is a more coarse grained rock. The individual grains of minerals can be seen by the naked eye. Many of the original minerals have been altered into flakes. Because it has been squeezed harder than slate it is often found folded and crumpled.

Schists are usually named by the main minerals that they are formed from. Bitotite mica schist, hornblende schist, garnet mica schist, and talc schist are some examples of this.

Gneiss is a high grade metamorphic rock. This means that gneiss has been subjected to more heat and pressure than schist. Gneiss is coarser than schist and has distinct banding.

This banding has alternating layers that are composed of different minerals. The minerals that compose gneiss are the same as granite. Feldspar is the most important mineral that makes up gneiss along with mica and quartz.

Gneiss can be formed from a sedimentary rock such as sandstone or shale, or it can be formed from the metamorphism of the igneouse rock grantite.

Gneiss can be used by man as paving and building stone. Non-Foliates are metamorphic rocks that have no cleavage at all. Quartzite and marble are two examples of non-foliates that we are going to study. Quartzite is composed of sandstone that has been metamorphosed.

Quartzite is much harder than the parent rock sandstone. It forms from sandstone that has come into contact with deeply buried magmas. Quartzite looks similar to its parent rock. The best way to tell quartzite from sandstone is to break the rocks. Sandstone will shatter into many individual grains of sand while quartzite will break across the grains. Marble is metamorphosed limestone or dolomite. Both limestone and dolomite have a large concentration of calcium carbonate CaCO3.

Marble has many different sizes of crystals. As grade of metamorphism increases, hydrous minerals become less hydrous, by losing H 2 O, and non-hydrous minerals become more common.

Types of Metamorphism Contact Metamorphism Contact metamorphism occurs adjacent to igneous intrusions and results from high temperatures associated with the igneous intrusion.

Classification of Metamorphic Rocks Classification of metamorphic rocks is based on mineral assemblage, texture, protolith, and bulk chemical composition of the rock. This series is listed below: rutile, sphene, magnetite tourmaline kyanite, staurolite, garnet, andalusite epidote, zoisite, lawsonite, forsterite pyroxenes, amphiboles, wollastonite micas, chlorites, talc, stilpnomelane, prehnite dolomite, calcite scapolite, cordierite, feldspars quartz This series can, in a rather general way, enable us to determine the origin of a given rock.

Some terms that describe this general bulk chemical composition are as follows: Pelitic. These rocks are derivatives of aluminous sedimentary rocks like shales and mudrocks. Because of their high concentrations of alumina they are recognized by an abundance of aluminous minerals, like clay minerals, micas, kyanite, sillimanite, andalusite, and garnet. Rocks that originally contained mostly quartz and feldspar like granitic rocks and arkosic sandstones will also contain an abundance of quartz and feldspar as metamorphic rocks, since these minerals are stable over a wide range of temperature and pressure.

Those that exhibit mostly quartz and feldspar with only minor amounts of aluminous minerals are termed quartzo-feldspathic. Calcareous rocks are calcium rich.

They are usually derivatives of carbonate rocks, although they contain other minerals that result from reaction of the carbonates with associated siliceous detrital minerals that were present in the rock.

At low grades of metamorphism calcareous rocks are recognized by their abundance of carbonate minerals like calcite and dolomite. With increasing grade of metamorphism these are replaced by minerals like brucite, phlogopite Mg-rich biotite , chlorite, and tremolite. At even higher grades anhydrous minerals like diopside, forsterite, wollastonite, grossularite, and calcic plagioclase. Just like in igneous rocks, the general term basic refers to low silica content. Basic metamorphic rocks are generally derivatives of basic igneous rocks like basalts and gabbros.

They have an abundance of Fe-Mg minerals like biotite, chlorite, and hornblende, as well as calcic minerals like plagioclase and epidote. Rocks that are rich in Mg with relatively less Fe, are termed magnesian. Such rocks would contain Mg-rich minerals like serpentine, brucite, talc, dolomite, and tremolite. In general, such rocks usually have an ultrabasic protolith, like peridotite, dunite, or pyroxenite. Rocks that are rich in Fe with little Mg are termed ferriginous.

Such rocks could be derivatives of Fe-rich cherts or ironstones. They are characterized by an abundance of Fe-rich minerals like greenalite Fe-rich serpentine , minnesotaite Fe-rich talc , ferroactinolite, ferrocummingtonite, hematite, and magnetite at low grades, and ferrosilite, fayalite, ferrohedenbergite, and almandine garnet at higher grades. Rocks that are characterized by the presence of Mn-rich minerals are termed manganiferrous. They are characterized by such minerals as Stilpnomelane and spessartine.

Classification Classification of metamorphic rocks depends on what is visible in the rock and its degree of metamorphism. Note that classification is generally loose and practical such that names can be adapted to describe the rock in the most satisfactory way that conveys the important characteristics. Three kinds of criteria are normally employed. These are: Mineralogical - The most distinguishing minerals are used as a prefix to a textural term.

Thus, a schist containing biotite, garnet, quartz, and feldspar, would be called a biotite-garnet schist. A gneiss containing hornblende, pyroxene, quartz, and feldspar would be called a hornblende-pyroxene gneiss.

A schist containing porphyroblasts of K-feldspar would be called a K-spar porphyroblastic schist. Chemical - If the general chemical composition can be determined from the mineral assemblage, then a chemical name can be employed. For example a schist with a lot of quartz and feldspar and some garnet and muscovite would be called a garnet-muscovite quartzo-feldspathic schist.

A schist consisting mostly of talc would be called a talc-magnesian schist. Protolithic - If a rock has undergone only slight metamorphism such that its original texture can still be observed then the rock is given a name based on its original name, with the prefix meta- applied.

Here you can see that the brown mica crystals biotite are not aligned. The nature of the parent rock controls the types of metamorphic rocks that can form from it under differing metamorphic conditions temperature, pressure, fluids. The kinds of rocks that can be expected to form at different metamorphic grades from various parent rocks are listed in Table Some rocks, such as granite, do not change much at the lower metamorphic grades because their minerals are still stable up to several hundred degrees.

On the other hand, some rocks can change substantially. Mudrock e. Schist and gneiss can also form from sandstone, conglomerate, and a range of both volcanic and intrusive igneous rocks. If a metamorphic rock is heated enough, it can begin to undergo partial melting in the same way that igneous rocks do.

The more felsic minerals feldspar, quartz will melt, while the more mafic minerals biotite, hornblende do not. When the melt crystallizes again, the result is light-coloured igneous rock interspersed with dark-coloured metamorphic rock. This mixed rock is called migmatite Figure Note that the foliation present in the metamorphic rock is no longer present in the igneous rock. Liquids cannot support a differential stress, so when the melt crystallizes, the foliation is gone.

These are folds look like they should be impossible because they are enveloped by rock which does not display the same complex deformation Figure How could those wiggly folds get in there without the rest of the rock being folded in the same way?

The answer to the ptygmatic fold mystery is that the folded layer is much stiffer than the surrounding layers. Geologos 22 3 , Skip to content Metamorphic rocks are broadly classified as foliated or non-foliated. Figure Scale bar: 1 mm. Left- An undeformed granitic rock containing the mica mineral biotite Bt , plagioclase feldspar Pl , potassium feldspar Kfs , and quartz Qtz. Right- A metamorphic rock mylonite resulting from extreme deformation of granitic rocks.

Quartz crystals have been flattened and deformed. The other minerals have been crushed and deformed into a fine-grained matrix Mtx. Click the image to view the original figure captions and access the full text. Each of these has a characteristic type of foliation Slate Slate Figure Left- Slate fragments resulting from rock cleavage. Right- The same rock type in outcrop. Left- A hand sample showing a satin texture. This is a characteristic that separates true quartzite from sandstone.

Quartzite is usually white to gray in color. Some rock units that are stained by iron can be pink, red, or purple. Other impurities can cause quartzite to be yellow, orange, brown, green, or blue. The quartz content of quartzite gives it a hardness of about seven on the Mohs Hardness Scale.

Its extreme toughness made it a favorite rock for use as an impact tool by early people. Its conchoidal fracture allowed it to be shaped into large cutting tools such as ax heads and scrapers. Its coarse texture made it less suitable for producing tools with fine edges such as knife blades and projectile points.

Obsidian , flint and agate were better suited for tools where sharpness was important. Quartzite scree: A steep slope covered with an unstable blanket of quartzite scree. Scree is a name used for resistant pieces of broken rock that cover a talus slope. This photo was taken near Begunje na Gorenjskem, Slovenia. A Creative Commons image by Pinky sl.

Most quartzite forms during mountain-building events at convergent plate boundaries where sandstone was deposited on a continental plate. There, the sandstone is metamorphosed into quartzite by the intense pressure of a plate collision and often by deep burial.

Compressional forces at the plate boundary fold and fault the rocks and thicken the crust into a mountain range. Quartzite is an important rock type in folded mountain ranges throughout the world.

Catoctin Mountain is part of the Blue Ridge Mountains. The Chimney Rock Formation in this area caps many of the ridges, drapes the flanks of the mountains as scree, and is made up mostly of quartzite. Quartzite is one of the most physically durable and chemically resistant rocks found at Earth's surface. When mountain ranges are worn down by weathering and erosion, less-resistant and less-durable rocks are destroyed, but the quartzite remains.

This is why quartzite is so often the rock found at the crests of mountain ranges and covering their flanks as large boulders, or as a surface litter of scree. Quartzite is also a poor soil-former. Unlike feldspars which break down to form clay minerals, the weathering debris of quartzite is quartz. It is therefore not a rock type that contributes well to soil formation.

For that reason it is often found as exposed bedrock with little or no soil cover. Fuchsitic Quartzite: A specimen of quartzite that contains significant amounts of green fuchsite, a chromium-rich muscovite mica. This specimen measures about 7 centimeters across and was collected from a small abandoned quarry where the flaggy rocks were produced and cut for use as decorative stones. Photograph by James St. John, used here under a Creative Commons license. Geologists have used the name "quartzite" in a few different ways, each with a slightly different meaning.

Today most geologists who use the word "quartzite" are referring to rocks that they believe are metamorphic and composed almost entirely of quartz. A few geologists use the word "quartzite" for sedimentary rocks that have an exceptionally high quartz content.