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).
An igneous rock is formed by the cooling and crystallization of molten rock. The term igneous is derived from ignius, the Latin word for fire. Scientists have divided igneous rocks into two broad categories based on where the molten rock solidified. Volcanic rocks (also called extrusive igneous rocks) include all the products resulting from eruptions of lava (flows and fragmented debris called pyroclasts).