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Uses of Conglomerate
Conglomerate has very few commercial uses. Its inability to break cleanly makes it a poor candidate for dimension stone, and its variable composition makes it a rock of unreliable physical strength and durability. Conglomerate can be crushed to make a fine aggregate that can be used where a low-performance material is suitable. Many conglomerates are…
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Conglomerate vs. Breccia
Conglomerate and breccia are similar rocks. They are both made of clasts over two millimeters in diameter. What’s the difference between conglomerate and breccia? The difference is in the shape of the clasts. Conglomerate is made up mostly of subrounded to rounded clasts. However, breccia is made up mostly of subangular to angular clasts. Sedimentary clasts can…
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How Does Conglomerate Form?
Conglomerate forms where sediments of rounded clasts at least two millimeters in diameter accumulate. It takes a strong water current to transport and produce a rounded shape on particles this large. Wind transport is unlikely to produce a conglomerate. The environment of deposition might be along a swiftly flowing stream or a beach with strong…
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What is the Composition of Conglomerate?
Conglomerate can have a variety of compositions. As a clastic sedimentary rock, it can contain clasts of any rock material or weathering product that is washed downstream or down current. The rounded clasts of conglomerate can be mineral particles such as quartz or feldspar, or they can be sedimentary, metamorphic, or igneous rock fragments. Clasts of quartzite, sandstone, limestone, granite, basalt, and gneiss are especially common. The matrix…
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What is Conglomerate?
Conglomerate is a clastic sedimentary rock made up of rounded clasts that are greater than two millimeters in diameter. The spaces between the clasts are generally filled with sand- and clay-size particles. The rock is bound together by a cement that is usually composed of calcite or quartz.
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Making Fire and Sharpening Steel
Chert is a very hard material that produces a spark when it is struck against steel. The heat from this spark can be used to start fires. A “flintlock” is an early firearm in which a charge of gunpowder is ignited by a flint hammer striking a metal plate (see photo). A variety of metamorphosed…
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Chert Used to Make Sharp Tools
Chert has very few uses today; however, it was a very important tool-making material in the past. Chert has two properties that made it especially useful: 1) it breaks with a conchoidal fracture to form very sharp edges, and, 2) it is very hard. The edges of broken chert are sharp and tend to retain…
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What Color is Chert?
Chert occurs in a wide variety of colors. Continuous color gradients exist between white and black or between cream and brown. Green, yellow, orange, and red cherts are also common. The darker colors often result from inclusions of mineral matter and organic matter. Abundant iron oxides in the chert can produce a red color. The…
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What is Chert’s Composition?
Chert is a microcrystalline silicon dioxide (SiO2). As chert nodules or concretions grow within a sediment mass, their growth can incorporate significant amounts of the surrounding sediment as inclusions. These inclusions can impart a distinctive color to the chert.
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How Does Chert Form?
Chert can form when microcrystals of silicon dioxide grow within soft sediments that will become limestone or chalk. In these sediments, enormous numbers of silicon dioxide microcrystals grow into irregularly-shaped nodules or concretions when dissolved silica is transported to the formation site by the movement of groundwater. If the nodules or concretions are numerous, they can grow large…