Coarsely crystalline and finely crystalline.
Texture determines whether an igneous rock is defined as Intrusive (coarsely crystalline) or Extrusive (finely crystalline). Intrusive Igneous Rocks. 1. Fig. 3.2: Intrusive igneous rocks form at some depth within the crust due to slow cooling of magma, resulting in formation of large crystals. Individual crystals can be seen with the naked eye. These rocks are termed texturally as coarsely crystalline or phaneritic. Igneous rocks are formed from the solidification of molten rock material. There are two basic types. Intrusive igneous rocks crystallize below Earth's surface and the slow cooling that occurs there allows large crystals to form. Examples of intrusive igneous rocks are diorite, gabbro, granite, pegmatite, and peridotite. Extrusive igneous rocks erupt onto the surface where they cool quickly to form small crystals. Some cool so quickly that they form an amorphous glass. Pictures and brief descriptions of some common igneous rock types are shown on this page. Diorite is a coarse-grained, intrusive igneous rock that contains a mixture of feldspar, pyroxene, hornblende and sometimes quartz. The specimen shown above is about two inches (five centimeters) across. These rocks include andesite, basalt, obsidian, pumice, rhyolite, scoria, and tuff. Pictures and brief descriptions of some common igneous rock types are shown on this page. Diorite is a coarse-grained, intrusive igneous rock that contains a mixture of feldspar, pyroxene, hornblende and sometimes quartz. The specimen shown above is about two inches (five centimeters) across. The rocks of the Highlands Province are a part of the Crystalline Appalachians.. This name refers to the term crystalline rock, a general term for igneous and metamorphic rock (as opposed to sedimentary rock) where the rock consists of minerals in an obviously crystalline state.  Igneous Rocks. Igneous rocks are crystalline solids which form directly from the cooling of magma. This is an exothermic process (it loses heat) and involves a phase change from the liquid to the solid state. The earth is made of igneous rock-at least at the surface where our planet is exposed to the coldness of space. Igneous rock is formed through the cooling and solidification of magma or lava. Igneous rock may form with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. This magma can be derived from partial melts of pre-existing rocks in either a planet's mantle or crust. Basalt is a common extrusive igneous rock and forms lava flows, lava sheets and lava plateaus. Some kinds of basalt solidify to form long polygonal columns. The Giant's Causeway found in Antrim, Northern Ireland is an example. The molten rock, with or without suspended crystals and gas bubbles, is called magma. Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means change in form. The original rock (protolith) is subjected to heat (temperatures greater than 150 to 200 °C) and pressure (1500 bars), causing profound physical and/or chemical change. Other minerals, such as olivines, pyroxenes, amphiboles, micas, feldspars, and quartz, may be found in metamorphic rocks, but are not necessarily the result of the process of metamorphism. These minerals formed during the crystallization of igneous rocks. Using food terms, it resembles baloney (unidentifiable components). Rhyolite has the same chemical and mineral content as granite. 4. andesite Andesite is the name of fine-grained igneous rocks that are midway in color and mineral composition between rhyolite and basalt. Andesites are commonly gray or some shade of medium brown.  The color is a reflection of the minerals present in the rock. Metamorphic rocks are those formed by altering igneous, sedimentary, or other metamorphic rocks by heat and/or pressure. The heat and pressure cause changes in the minerals present, as well as rearranging the minerals in the rocks. Crystalline rocks refers to either igneous or metamorphic rocks. Much more information about the rocks in general, rocks of Pennsylvania, and the minerals of which they are composed, can be found in our publication ES1: Rocks and Minerals of Pennsylvania. Intrusive igneous rocks are formed from magma that cools and solidifies within the crust of a planet, surrounded by pre-existing rock (called country rock); the magma cools slowly and, as a result, these rocks are coarse grained. The mineral grains in such rocks can generally be identified with the naked eye. Basalt is a common extrusive igneous rock and forms lava flows, lava sheets and lava plateaus. Some kinds of basalt solidify to form long polygonal columns. The Giant's Causeway found in Antrim, Northern Ireland is an example. The molten rock, with or without suspended crystals and gas bubbles, is called magma.
http://www.uh.edu/~geos6g/1330/igneous.html http://geology.com/rocks/igneous-rocks.shtml http://geology.com/rocks/igneous-rocks.shtml http://3dparks.wr.usgs.gov/nyc/highlands/highlands.html http://jersey.uoregon.edu/~mstrick/AskGeoMan/geoQuerry13.html https://en.wikipedia.org/wiki/Igneous_rock https://en.wikipedia.org/wiki/Metamorphic_rock http://skywalker.cochise.edu/wellerr/GLG101/GLG101-igneous-rocks.htm http://dcnr.state.pa.us/topogeo/groundwater/rocktypes/ https://en.wikipedia.org/wiki/Igneous_rock
names of crystalline igneous rocks