TRANSVERSE CONTRACTION JOINTS. The primary purpose of transverse contraction joints is to control the cracking that results from the tensile and bending stresses in concrete slabs caused by the cement hydration process, traffic loadings, and the environment.
Diamonds are found in igneous rock which is brought to the surface of the earth by volcanic eruptions bringing magma to the surface. Diamond itself is strictly an allotrope of the element carbon, a mineral, one form of crystal that can be created from carbon.
1 Aphanitic igneous rocks have a fine-grained texture and most of their crystals are too small to see with the naked eye. 2  You will need to use a magnifying glass to observe the crystals in aphanitic rocks. 3  Igneous rocks that form too quickly for crystals to form have what is called a glassy texture. An example of an intrusive rock is granite. 2  When magma is above the earth's crust, it is known as lava. 3  Extrusive rocks form through very fast cooling of lava above the Earth's surface. 4  Extrusive rocks have very small, almost microscopic crystals.