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.
Refer to Igneous Rocks Photos for more visual examples of each of these igneous rock types. glassy texture 1. obsidian Obsidian is volcanic glass without gas bubbles. It is usually black or dark brown in color and breaks with a conchoidal (shell-like) fracture.Be careful not to cut yourself on the sharp edges.efer to Igneous Rocks Photos for more visual examples of each of these igneous rock types. glassy texture 1. obsidian Obsidian is volcanic glass without gas bubbles. It is usually black or dark brown in color and breaks with a conchoidal (shell-like) fracture. Be careful not to cut yourself on the sharp edges.