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Geology of Urban Watersheds
Published in Daniel T. Rogers, Urban Watersheds, 2020
There are four basic types of sand deposits (Pettijohn et al. 1987; Boggs 2000): Quartz arenites consist almost entirely of quartz grains, are usually well-sorted and well-rounded. Quartz arenite deposits result from extensive weathering, so they consist of only the most resistant minerals. Figure 2.25 is an example of a quartz arenite sand that is medium grain, well-sorted, with sub- to well-rounded grains.Arkoses are sand deposits with a composition of 25% feldspar or more. The grains tend to be poorly rounded and less well sorted than quartz arenites. Arkoses originate from rapidly eroding granitic and metamorphic rock where physical weathering is dominant.Lithic sand deposits contain many fragments derived from fine-grained materials, mostly shales, volcanic rocks, and fine-grained metamorphic rocks.Greywacke is a heterogeneous mixture of rock fragments and angular grains of quartz and feldspar; the sand grains become surrounded by a fine-grained clay matrix.
Silurian and Lower Devonian
Published in W. A. Peck, J.L. Neilson, R.J. Olds, K.D. Seddon, Engineering Geology of Melbourne, 2018
Greywacke is a rock composed of poorly sorted angular to sub-angular grains of rock fragments and minerals such as quartz, feldspar and mica and is typically grey or greenish grey. The greywackes are fine to coarse grained and may be pebbly.
Natural aggregate sources and production
Published in Mark Alexander, Sidney Mindess, Aggregates in Concrete, 2005
Mark Alexander, Sidney Mindess
Chert is the general term for a group of very fine-grained siliceous sedimentary rocks of microcrystalline or cryptocrystalline quartz, chalcedony, or opal, formed by chemical deposition and consolidation. They may be dense and very tough and of darker colour, or porous usually of lighter colour. Chert occurs frequently as lenses in calcareous deposits, or in extensive beds, and is often found in sands and gravels. Cherts are often alkali-reactive and should be treated with caution. Dense, black or grey chert is called flint. Felsites are taken to refer collectively to a group of usually light-coloured igneous rocks, including rhyolite, dacite, andesite, and trachyte, which are the equivalents of granite, quartz diorite, diorite, and syenite respectively. When microcrystalline or containing natural glass, they may be potentially alkali-reactive in concrete. When used as crushed materials, the shape may be characteristically flaky and elongated. Greywackes are grey to greenish-grey sedimentary or metamorphic rocks containing angular quartz, feldspar grains, and sand-sized fragments in a matrix of clay or shale.
Effects of Abrasive Rock Type on CVF-Dependent Performance Trends of White Cast Irons in the Inner Circumference Abrasion Test
Published in Tribology Transactions, 2022
E. Demirer, Hamid Pourasiabi, L.J. McInnes, R. Knibbe, J.D. Gates
Two of the most commonly encountered rock types in the Earth’s crust are basalt and granite. Basalts are fine-grained igneous rocks in which the primary minerals are plagioclase (Na-Ca feldspars) and pyroxenes (such as augite, diopside, or spodumene). Informally, the term “granite” is often used to denote a fairly broad range of relatively coarse-grained, inhomogeneous igneous rock types. The primary minerals in granite are feldspars (both orthoclase and plagioclase) and quartz. Greywacke is a sedimentary rock type containing similar primary minerals as granite but in a compact, clay-fine matrix. This results in a slightly lower hardness for greywacke than granite. Table 1 shows the published values of Mohs hardness for these minerals.
3D Geological modelling of the Taupo Volcanic Zone as a foundation for a geothermal reservoir model
Published in New Zealand Journal of Geology and Geophysics, 2018
Sarah D. Milicich, Sophie C. Pearson-Grant, Samantha Alcaraz, Paul A. White, Constanze Tschritter
Greywacke typically has very low intergranular permeability, though fracture permeability can be common. The typical range of porosity for greywacke is 0.02–0.2 (Wood et al. 2001). Intrinsic permeability within the greywacke basement is low, with macroscopic fault–fracture networks largely controlling fluid flow at depth (Rowland and Sibson 2004; McNamara et al. 2014).
Nanomechanical mapping of rejuvenated asphalt binders
Published in Road Materials and Pavement Design, 2021
I. Holleran, E. Masad, G. Holleran, Y. Wubulikasimu, J. Malmstrom, D. J. Wilson
Two types of aggregates, melter slag and greywacke, were used in PA mixes from which PA-1 and PA-2 binders were extracted. Greywacke is a sedimentary type aggregate consisting of a mixture of sandstone, mudstone, and siltstones. Melter slag is a by-product from steel manufacturing where iron sand is utilised.