Methylphenidate is a commonly prescribed psychostimulant and works by increasing the activity of the central nervous system. It produces such effects as increasing or maintaining alertness, combating fatigue, and improving attention. The short-term benefits and cost effectiveness of methylphenidate are well established.
(image copied from here). 1  Igneous Rocks: form by crystallizing melted material (magma). 2  They can form either on the surface (extrusive igneous rocks), or deep in the crust (intrusive or plutonic igneous rocks).
1 Magma is molten rock that flows beneath the earth's surface. 2  Igneous rocks are formed by cooling magma. 3  The location of the formation of the rock, as well as how fast the magma cools will determine the type of igneous rock. 4  Intrusive rocks form from the cooling of magma deep beneath the earths surface. Igneous rocks that form too quickly for crystals to form have what is called a glassy texture. 2  Obsidian is the only glassy igneous rock, and can be identified by its dark color. 3  This looks like dark black glass.