Breccia forms when shards of rock, over at least 0.08 inches in length, are cemented together a relatively short distance from where they were originally broken off. Often this occurs at the base of an outcrop of rock where mechanical weathering occurs.Know More
Breccia is a sedimentary rock where sharp, angular pieces of other rocks are stuck together. They can be bound together with either a mineral cement or a mix of smaller rock fragments. It is very similar to conglomerate, except conglomerate contains rounded pieces of rock instead of angular ones. Breccia constituents are sharp because they are not carried a great distance before becoming embedded in sediment. Otherwise, the edges would be worn down.
Breccia has no particular mineral composition, and is a term for any sedimentary rock matching its physical description. They are often a mix of different minerals, but if one type of mineral predominates, it can be called limestone breccia, granite breccia or whatever name best characterizes the source rock. Because of the variety of mineral compositions, the color and general appearance of breccias vary widely. There are few human uses for breccias, although the breccias from certain private quarries are used for various decorative applications.Learn more about Geology
Gabbro, a type of intrusive igneous rock, is formed when magma cools and solidifies inside the crust of the Earth. Because it cools slowly, it is coarsely grained.Full Answer >
Graphite is a polymorph of carbon typically formed through the metamorphism of organic material found in mineral deposits. It can also appear during the formation of igneous rocks or as nodules inside of iron meteorites.Full Answer >
Basalt is primarily formed by the extrusion of lava flows onto the surface of the earth during a volcanic eruption. The intrusion of a narrow sill or igneous dike below the crust also results in the formation of basalt.Full Answer >
Chert is most often created when microcrystals of silicon dioxide are formed within soft sediments that over time will turn into chalk or limestone. When large amounts of silicon dioxide microcrystals are present in the sediment, they start to clump together and can eventually form whole layers of chert within a limestone deposit.Full Answer >