Sandstone composition - Sandstone is a sedimentary rock composed of sand-size grains of mineral, rock, or organic material. It also contains a cementing material that binds the sand grains together and may contain a matrix of silt- or clay-size particles that occupy the spaces between the sand grains.

 
The composition of the single quartz particle as the core surrounded by various components of the matrix was regarded as a simple unit of feldspar sandstone. The unit contained all the basic elements in the composition of feldspar sandstone, as shown in Figure 14(c). During the dry-wet cycles, water first invaded from the outside to the …. Kerr mcgee oil and gas onshore lp

Sandstone is a sedimentary rock which forms from cemented sand-sized clasts. It forms when sand layers are buried under sediments of sand. 1.2 Composition. 1.2.1 Mineral Content. Calcite, Clay, Clay Minerals, Feldspar, Micas, Quartz. 1.2.2 Compound Content. Aluminium Oxide, CaO, Iron (III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide.Sandstone is a sedimentary rock which forms from cemented sand-sized clasts. It forms when sand layers are buried under sediments of sand. 1.2 Composition. 1.2.1 Mineral Content. Calcite, Clay, Clay Minerals, Feldspar, Micas, Quartz. 1.2.2 Compound Content. Aluminium Oxide, CaO, Iron (III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide. Sandstone is a sedimentary rock composed of sand-size grains of mineral, rock, or organic material. It also contains a cementing material that binds the sand grains together and may contain a matrix of silt- or clay-size particles that occupy the spaces between the sand grains.The geological development history of Miocene deposits in three sedimentary basins as Phu Khanh, Nam Con Son and Tu Chinh - Vung May is actually a depositional evolution in relation to sea level change and tectonic movement. The Miocene deposits in three basins were formed in three cycles corresponding to three depositional sequences: …Arkose is a feldspar-rich sandstone. It is commonly coarse-grained and usually either pink or gray (depending on the color of feldspar). Arkose is a type of sandstone that contains lots of feldspar grains. A sample from the precambrian of Finland found on the northwestern coast of Estonia where it was left by the receding Scandinavian ...Some sandstone names indicate the rock’s mineral composition. Quartz sandstone contains predominantly quartz sediment grains. Arkose is sandstone with significant amounts of feldspar, usually greater than 25%. Sandstone that contains feldspar, which weathers more quickly than quartz, is useful for analyzing the local geologic history.Jan 23, 2019 · Sandstone also commonly known as arenite is a clastic sedimentary rock composed mainly of sand-sized minerals or rock grains of about 0.05mm to 2cm, matrix, cement and pore space. (figure 2). . . Figure 2: A microscopic photograph of a Nubia sandstone under the polarizing microscope. It is composed of entirely of monocrystalline, subrounded ... Medium-grained rocks composed mainly of sand are called sandstone, or sometimes arenite if well sorted. Sediment grains in sandstone can having a wide variety of mineral compositions, roundness, and sorting. Some …Abstract. The detrital mineralogy of sandstones is affected significantly by depositional environment. The imprint of the environment is recorded as the relative abundance and size of individual detrital species. Differences between environments within any one basin are accompanied by concomitant changes in detrital-sediment composition.Arkose. Arkose ( / ˈɑːrkoʊs, - koʊz /) or arkosic sandstone [1] is a detrital sedimentary rock, specifically a type of sandstone containing at least 25% feldspar. [2] [3] Arkosic sand is sand that is similarly rich in feldspar, and thus the potential precursor of arkose. Quartz is commonly the dominant mineral component, and some mica is ...Evolutionary trends in sandstone composition within individual basins or sedimentary provinces commonly reflect changes in tectonic setting through time, or erosional modification of provenance terranes. Forearc sandstone suites typically evolve from feldspatholitic petrofacies of volcaniclastic nature, through lithofeldspathic petrofacies of ...Sandstone is composed of sand-sizes (0.062 - 2 mm) silicate particles. The silicate can be quartz or feldspar. Both elements are highly resistant to weathering events on the earth's surface. The sand grains are conveniently called framework grains. Sandstones with more than 30% grains of gravel are classified as conglomerates or breccia.Sep 4, 2019 · In this study, a comprehensive literature review was performed to build a database containing petrographic and mechanical properties for sedimentary rock types. A subset of this database ... Reddish brown. Miscellaneous. Feels sandy; Immature. Depositional Environment. Alluvial Fan, or Braided Stream. Type Sedimentary Rock Origin Detrital/Clastic Texture Clastic; Medium-grained (0.06 – 2 mm) Composition Feldspar, Quartz Color Reddish brown Miscellaneous Feels sandy; Immature Depositional Environment Alluvial Fan, or Braided Stream. The surrounding rock is mainly metamorphosed sandstone characterized by variable residual sandy, massive structure, and dominated by quartz (about 25%) and feldspar (about 40%), with mica and Fe-bearing minerals to be the secondary minerals. ... The lithium isotopic composition of different aquifers in the Puna area, Argentina, shows …From lofty churches and imposing public buildings to vernacular houses and field walls, much of Britain's built heritage was 'written' in sandstone. Graham Lott of the British Geological Survey looks at the sandstones quarried and used for construction around Britain, the decline in the scale and diversity of building sandstone production since its …Mar 29, 2023 · Depending on the differences of rock strength caused by rock types shown in Fig. 2 a, this section is divided into three parts which respectively show the effects of mineral composition on sandstone, carbonate, and shale rocks. 3.1. Effects of mineral composition on sandstone strength Photomicrographs of feldspathic (L) and lithic (R) greywacke. The top images are in plane-polarized light; the bottom images are in cross-polarized light.Cements fill the pore spaces. Closeup of Pharaoh Menkaure's greywacke statue, 25th century BCE, from the Egyptian Museum in Cairo. Greywacke or graywacke (German grauwacke, signifying a grey, …Sandstone Sandstone is a sedimentary rock ... arkose or arkosic sandstones, which have a high (>25%) feldspar content and a composition similar to granite.The composition of sandstone is primarily determined by the source material and deposition environment. Most sandstones are composed of quartz, feldspar, and rock fragments, but other minerals like micas, heavy minerals, and clay minerals can also be present. The cementing agents in sandstone include silica, calcium carbonate, and iron oxide.Jan 4, 2018 · Sandstone (sometimes known as arenite) is a clastic sedimentary rock composed mainly of sand-sized minerals or rock grains. Most sandstone is composed of quartz or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any color, but the most common colors are tan, brown, yellow, red, grey, pink ... Most sandstones are made up of mixtures o a very small number of dominant framework components, like quartz, feldspars, and rock fragments are commonly abundant enough to be important in sandstone classification. ... crawling can destroy primary sedimentary structures but commonly unchange a mineralogical and chemical …Sandstone reservoirs form extensive stratigraphic traps. Many of the sandstones change composition within the sandstone unit; at this point, they are said to pinchout. Others represent ancient upland river channels that have left sand in the channel that has been converted into sandstone. Often these sand channels are stacked one on top of ...PDF | The discriminative power of four analytical approaches to sandstone composition is evaluated with respect to the separation of different... | Find, read and …The detailed petrographic analysis of sandstone composition includes framework grains, heavy minerals, and elements, and elemental analysis can provide the best way to infer the depositional history, weathering conditions at the source of sediments, and identification of the sediment provenance (Taylor and McLennan 1985; Dickinson 1985; Zhang ...Observed variations in the sandstones’ composition with regards to geographic location and depth are associated with variations in the erosion of parent rocks, including subsequent modification ...) Quartz Sandstone B, R, S, C All Sugary, sandy, or crystalline; can sometimes see quartz sand grains fused together; grains won’t rub off like sandstone. Skarn Impure limestone or chert, arkose, greywacke… C All Crystalline; usually with large cryst als, including calcite, quartz, garnet, epidote, pyroxene and other crysandstone: bioturbation: hummocky cross beds: Upper shoreface: planar sand: sandstone: bioturbation: ... tourmaline-rutile maturity index and the interdependence of the composition of heavy mineral assemblages with the gross composition and texture of sandstones. J. Sediment. Res. 32, (1962). 45. Eisma, D. Intertidal deposits: River mouths ...Sandstone is a sedimentary rock composed of sand-size grains of mineral, rock, or organic material. It also contains a cementing material that binds the sand grains together and may contain a matrix of silt- or clay-size particles that occupy the spaces between the sand grains.Several schemes were proposed and debated; few were accepted. One of the central topics of discussion was the relative importance of sandstone texture versus sandstone composition. A classification based on texture alone was deemed inadequate; if the rock or sediment had >50% sand, then it was a sandstone, or arenite.Sandstone is a sedimentary rock formed from sand-sized mineral particles, while shale is formed from clay or silt-sized particles. Sandstone has a coarser texture and is more porous than shale, with a fine, laminated texture. Shale is more prone to breaking along its layers due to its fine-grained composition, whereas sandstone is more ...Tendency to chemical cement. Ash: unconsolidated fragments under. 4 mm. Tuff: consolidated ash. Volcanic Breccia: angular fragments over 4 mm. Agglomerate: large proportion (>25%) of bombs. These rocks are classified on the proportions of vitric, crystal (mineral), or lithic material they contain, for example, "vitric lithic ash," or "crystal ... Reddish brown. Miscellaneous. Feels sandy; Immature. Depositional Environment. Alluvial Fan, or Braided Stream. Type Sedimentary Rock Origin Detrital/Clastic Texture Clastic; Medium-grained (0.06 – 2 mm) Composition Feldspar, Quartz Color Reddish brown Miscellaneous Feels sandy; Immature Depositional Environment Alluvial Fan, or Braided Stream.A composite cell is any one of a collection of different types of cells that all have the same general chemical makeup that perform the same functions. Because many cells are very similar to one another in these ways, it is possible to gene...Apr 23, 2023 · Chemical Composition. Quartzite is a metamorphic rock made from quartz sandstone, a sedimentary rock predominantly composed of the silicate mineral quartz. The chemical composite of the quartz minerals is silicon dioxide, written SiO2. The metamorphic forces of heat and pressure force the quartz minerals to bind together and crystallize into a ... Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20 - 25% of all sedimentary rocks. Sandstone Sedimentary rock Cut slab of sandstone Composition Typically quartz and feldspar; lithic fragments are also common.Beyond that, sandstone is much easier to work with than limestone, concrete, or cement; it means you also pay less for labor costs. Overall, when it comes to the affordability of sandstone vs limestone, sandstone is a pretty clear winner. Composition of Limestone and Sandstone. Limestone has a very chalky texture thanks to its calcite …In this study, a comprehensive literature review was performed to build a database containing petrographic and mechanical properties for sedimentary rock types. A subset of this database ...The composition (sandstone) and presence of stromatolites indicate that this area was previously a very shallow sea. The rock layers in the Grand Canyon Supergroup have been tilted, whereas the other rocks above this set are horizontal. This is …Composition: Mainly quartz and feldspar and a small amount of mica and other minerals cemented with calcite Color: Pink, red or grayish, lighter than graywacke …7 jun 2019 ... One of the central topics of discussion was the relative importance of sandstone texture versus sandstone composition. A classification ...Sandstone is a sedimentary rock formed from sand-sized mineral particles, while shale is formed from clay or silt-sized particles. Sandstone has a coarser texture and is more porous than shale, with a fine, laminated texture. Shale is more prone to breaking along its layers due to its fine-grained composition, whereas sandstone is more ...The classification of the sandstone can be done basically on two important factors i.e. texture as well as mineral composition. The two famous schemes of classifications are given by Robert H. Dott (1964) who was an American Petrologist and whose scheme was based on the concepts of P.D. Krynine & F.J. Pettijohn whereas …In cement industry silica sanded crushed sandstone are used as an additive to make for silica deficiencies in the raw mill. The silica content should be 65 – 98%, Fe2O3 – 0.5- 6% Al2O3: 3.58January 01, 2006 Cite Share Permissions Abstract A popular model proposed by W. R. Dickinson and co-workers in the early 1980s relates the composition of sandstones to …Shale is a rock composed mainly of clay-size mineral grains. These tiny grains are usually clay minerals such as illite, kaolinite, and smectite. Shale usually contains other clay-size mineral particles such as quartz, chert, and feldspar. Other constituents might include organic particles, carbonate minerals, iron oxide minerals, sulfide ... Aug 22, 2023 · Siltstone. Siltstone is a clastic sedimentary rock that formed from grains whose sized between that of sandstone and mudstone. It can found different environmental conditions different color and textures. Siltstone generally are red and gray color with flat bedding planes. Darker colored siltstone have plant fossils and other carbon-rich matter. Sandstone, lithified accumulation of sand-sized grains (0.063 to 2 mm [0.0025 to 0.08 inch] in diameter). It is the second most common sedimentary rock after shale, constituting about 10 to 20 percent of the sedimentary rocks in the Earth’s crust.Arkose. Arkose ( / ˈɑːrkoʊs, - koʊz /) or arkosic sandstone [1] is a detrital sedimentary rock, specifically a type of sandstone containing at least 25% feldspar. [2] [3] Arkosic sand is sand that is similarly rich in feldspar, and thus the potential precursor of arkose. Quartz is commonly the dominant mineral component, and some mica is ...Lithology means "the composition or type of rock such as sandstone or limestone." These few words belie a host of details about reservoir rocks: Their depositional and diagenetic history ... mica, and other rock grains. This association is known widely as "shale." In sandstone reservoirs, clay-mineral content typically ranges from 0 to ...Limestone is a very common sedimentary rock consisting of calcium carbonate (more than 50%). It is the most common non-siliciclastic (sandstone and shale are common siliciclastic rocks) sedimentary rock.Limestones are rocks that are composed of mostly calcium carbonate (minerals calcite or aragonite). Carbonate rocks where the dominant …Its formation occurs through geological processes involving the deposition, compaction and cementation of sandy sediments over millions of years. Sandstone ...Shale. Shale is a laminated or fissile clastic sedimentary rock that composed of predominance of silt and clay other minerals , especially quartz and calcite. Characteristic properties of shale is breaks along thin laminae or parallel layering or bedding called fissility. It is most abundant sedimentary rock.Sandstone also commonly known as arenite is a clastic sedimentary rock composed mainly of sand-sized minerals or rock grains of about 0.05mm to 2cm, matrix, cement and pore space. (figure 2). . . Figure 2: A microscopic photograph of a Nubia sandstone under the polarizing microscope. It is composed of entirely of monocrystalline, subrounded ...From lofty churches and imposing public buildings to vernacular houses and field walls, much of Britain's built heritage was 'written' in sandstone. Graham Lott of the British Geological Survey looks at the sandstones quarried and used for construction around Britain, the decline in the scale and diversity of building sandstone production since its …What is Sandstone? Sandstone is a sedimentary rock composed of sand-size grains of mineral, rock, or organic material. It also contains a cementing material that binds the sand grains together and may contain a matrix of silt- or clay-size particles that occupy the spaces between the sand grains. 4.Total Rock Composition Component Proportion (%) Quartz 78 Feldspar 60 Rock fragments 36 Matrix 126 Total: 300 Total Q, F, and L: 174 Framework Grain Composition Component Proportion (%) Quartz (78/174) 45 Feldspar (60/174) 34 Lithic (36/174) 21 Total: 100 Sample Point Count Composition at 300 points is identified.Limestone is a very common sedimentary rock consisting of calcium carbonate (more than 50%). It is the most common non-siliciclastic (sandstone and shale are common siliciclastic rocks) sedimentary rock.Limestones are rocks that are composed of mostly calcium carbonate (minerals calcite or aragonite). Carbonate rocks where the dominant …Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary.Type Sedimentary Rock Origin Detrital/Clastic Texture Clastic; Medium-grained (0.06 – 2 mm) Composition Quartz Color White to light tan Miscellaneous Feels sandy; Mature Depositional Environment Beach – Barrier Island, Nearshore Continental Shelf, Nearshore Lake, Stream Channels, or Dunes17 ago 2014 ... Total Rock Composition Component Proportion (%) Quartz 78 Feldspar 60 Rock fragments 36 Matrix 126 Total: 300 Total Q, F, and L: 174 Framework ...Limestone and Sandstone Composition. In general, limestone is defined as being composed of calcium carbonate. Calcium carbonate often comes from plant and animal skeletons and remnants including the shells of mollusks. Sandstone, on the other hand, is not described as coming from any one substance. It consists of sand sized debris, which ...Nov 15, 2022 · Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) mineral particles or rock fragments. Most sandstone is composed of quartz or feldspar (both silicates) because they are the most resistant minerals to weathering processes at the Earth's surface, as seen in Bowen's reaction series. Like uncemented sand, sandstone may be any color due to impurities within the ... Sandstone is a clastic sedimentary rock made up mainly of sand-size (1/16 to 2 millimeter diameter) weathering debris. ... Seeing and handling the rocks will help you understand …Type Sedimentary Rock Origin Detrital/Clastic Texture Clastic; Medium-grained (0.06 – 2 mm) Composition Quartz Color White to light tan Miscellaneous Feels sandy; Mature Depositional Environment Beach – Barrier Island, Nearshore Continental Shelf, Nearshore Lake, Stream Channels, or Dunes The Upper Triassic Yanchang Formation consists of10 units from Chang 10 at the base to Chang1 at the top, which reflects the entire evolution of the basin from ...This reddish rock is arkose, a young feldspathic sandstone. Andrew Alden / Wikimedia Commons. Arkose is a raw, coarse-grained sandstone deposited very near its source that consists of quartz and a significant proportion of feldspar.. Arkose is known to be young because of its content of feldspar, a mineral that usually degrades quickly into …modal composition can be obtained by comparing the sandstone field-of-view with the diagrams of Fig. 2.49, which show the appearance of different percentages of grains in circular and square fields. A very rough esti-mate only of a sandstone’s composition can be made in the field through close scrutiny with a hand-lens. Provenance is the source rocks before reworking process, sandstone can composed by igneous rock, metamorphic rock or other sedimentary rock fragment. …The Jumara Dome sediments were deposited during sea-level fluctuating, and were interrupted by storms in the shallow marine environment. The sandstones are generally medium-grained, moderately sorted, subangular to subrounded and of low sphericity. The sandstones are mineralogically mature and mainly composed of quartzarenite and subarkose.Depending on the differences of rock strength caused by rock types shown in Fig. 2 a, this section is divided into three parts which respectively show the effects of mineral composition on sandstone, carbonate, and shale rocks. 3.1. Effects of mineral composition on sandstone strengthFigure 16. Rock varnish on sandstone. (A) Rock varnish comprising, from base to top, clay infillings of packing pores, followed by a dense opaque Mn/Fe oxide-rich layer, followed by a thin clay coating (Central Sahara) (XPL). (B) SEM image of a similar feature. Sign in to download full-size image.Jacobsville Sandstone is a red sandstone formation, marked with light-colored streaks and spots, primarily found in northern Upper Michigan, portions of Ontario, and under much of Lake Superior. Desired for its durability and aesthetics, the sandstone was used as an architectural building stone in both Canada and the United States. The stone ...5.2.1 Stratified rocks. Sedimentary rocks are formed by the deposition and subsequent cementation of materials on Earth’s surface and within bodies of water. Examples of sedimentary rocks include chalk, limestone, shale, quartz- lithic sandstone, conglomerate, chert, carbonaceous mudstone, and coal seams.Introduction to Sedimentary Rock Texture and Composition in Thin Section. Activity developed by Dr. Rachel Walters ([email protected]) Department of Geological Sciences, University of Florida ... Even though sandstones are by definition composed predominantly of sand-sized grains they can still be described as poorly sorted if there is a ...31) Which of these clastic rocks exhibits the least maturity? A) conglomerate B) sandstone C) breccia D) shale E) all of the above -Answer: __ 32) The sedimentary rock type which is altered organic remains is A) salt. B) chalk. C) bioclastic limestone. D) coal. E) shale. -Answer: __ 33) A rock formed from gravel is called A) conglomerate. B) peat.Quartzite forms when pure or nearly pure quartz sandstone undergoes intense heating and pressure usually related to tectonic compression. Geologically speaking, quartzite formation involves two types of metamorphisms: contact and Barrovian. Quartzite can form by either or both of these processes. 1.Sandstone (sometimes known as arenite) is a clastic sedimentary rock composed mainly of sand-sized minerals or rock grains. Most sandstone is composed of quartz or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any color, but the most common colors are tan, brown, yellow, …Sedimentary rocks are formed via the breakdown and redeposition of other materials, often older rocks. Sedimentary rocks are classified by their dominant particle size (sand, silt, or clay) and their mineral composition. Classic sedimentary rocks (i.e., sandstone or shale) are composed of minerals, grains and rock fragments derived from older rocks; while …Biochemical sedimentary rocks are composed of the shells of dead organisms, but organic sedimentary rocks are composed of _____. Choose one: A. living organisms B. bones of dead organisms C. organic material/compounds of dead organisms D. tracks and burrows of dead organismsSandstone is a sedimentary rock formed from cemented sand-sized clasts. The cement that binds the clasts can vary from clay minerals to calcite, silica or iron oxides. Sandstone can be further divided according to: Clast size - fine (0.06-0.2mm), medium (0.2-0.6mm), coarse (0.6-2mm); Sorting - a sandstone comprising a mixture of clast sizes is ...

Greywacke. Greywacke is variation of sandstone that saperate from other to hardness, dark color, and poorly sorted angular grains of quartz and feldspar .. It is a textural immature sedimentary rock found in the Paleozoic layers. Larger grains can be from sand to pebble length, and matrix materials are in the order of 15% by volume of rocks.. Scott whisnant

sandstone composition

Sandstone Sandstone is a sedimentary rock ... arkose or arkosic sandstones, which have a high (>25%) feldspar content and a composition similar to granite.Later, after having been deeply buried, reducing fluids composed of water and hydrocarbons flowed through the thick red sand which once comprised the Navajo Sandstone. The dissolution of the iron coatings by the reducing fluids bleached large volumes of the Navajo Sandstone a brilliant white. Quartzite forms when pure or nearly pure quartz sandstone undergoes intense heating and pressure usually related to tectonic compression. Geologically speaking, quartzite formation involves two types of metamorphisms: contact and Barrovian. Quartzite can form by either or both of these processes. 1.Like asphalt, composite roof shingles are cost-effective and simple to install. But they also have a range of other benefits. Here's what you should know about these synthetic shingles. Expert Advice On Improving Your Home Videos Latest Vie...The author has collected 168 chemical analyses from the literature. All analyses with less than 5 per cent Al 2 O 3 ("quartzite" clan) were removed. The remaining analyses were divided on a tectonic basis into three clans; taphrogeosynclinal, eugeosynclinal, and others (mainly exogeosynclinal).Abstract. The detrital mineralogy of sandstones is affected significantly by depositional environment. The imprint of the environment is recorded as the relative abundance and size of individual detrital species. Differences between environments within any one basin are accompanied by concomitant changes in detrital-sediment composition.The classification of the sandstone can be done basically on two important factors i.e. texture as well as mineral composition. The two famous schemes of classifications are given by Robert H. Dott (1964) who was an American Petrologist and whose scheme was based on the concepts of P.D. Krynine & F.J. Pettijohn whereas …The Yolla Bolly terrane was first defined in the Yolla Bolly Mountains of northern California. Based on similarities in lithology, sandstone composition, age, and metamorphic state, some Franciscan rocks in the northern and eastern Bay Area have been assigned to the Yolla Bolly terrane (Blake et al., 1984).Download scientific diagram | Interpretation of the sandstone composition from the petrography of the Madzaringwe Formation in the Tshipise-Pafuri basin ...Later, after having been deeply buried, reducing fluids composed of water and hydrocarbons flowed through the thick red sand which once comprised the Navajo Sandstone. The dissolution of the iron coatings by the reducing fluids bleached large volumes of the Navajo Sandstone a brilliant white.The physical and chemical effects of water change the original physical composition and spatial structure of rock, resulting in secondary porosity. ... The impact of diagenetic fluid–rock reactions on Rotliegend sandstone composition and petrophysical properties (Altmark area, central Germany). Environ Earth Sci 67(2):369–384. Article ...Quartzite is a nonfoliated metamorphic rock composed almost entirely of quartz. It forms when a quartz-rich sandstone is altered by the heat, pressure, and chemical activity of metamorphism. Metamorphism recrystallizes the sand grains and the silica cement that binds them together. .

Popular Topics