Igneous Rocks

Pumice is a volcanic rock that consists of highly vesicular rough textural rock glass. It generally light colored. It is created when gas-saturated liquid...

Rhyolite is a felsic extrusive rock. Due to the high silica content, rhyolite lava is very viscous. It flows slowly, like tooth paste squeezed out of a tube, and tends to pile up and biçim lava domes. If rhyolite magma is gas rich it can erupt explosively, forming a frothy solidified magma called pumice (a very lightweight, light-coloured, vesicular form of rhyolite)

Obsidian is an igneous rock that forms when molten rock material cools so rapidly that atoms are unable to arrange themselves into a crystalline structure. It is an amorphous material known as a "mineraloid." The result is a volcanic glass with a smooth uniform texture that breaks with a conchoidal fracture .

Medium or coarse grained rocks, gabbros Dark green pyroxene in principle (augite and smaller orthopyroxene amounts plus white or green colored plagioclase and black, millimeter sized grains of magnetite and / or ilmenite.

Diorite is coarse – grained intrusive igneous rock that commonly mineralogy is plagioclase feldspar and dark colored minerals such as hornblende and biotite.It usually occurs dikes, sills and intrusions with continental crust . Diorite is usually grey to dark-grey in colour, but it can also be black or bluish-grey, and frequently has a greenish cast.

Pegmatite is an igneous rock that form end of the stage a magma’s crystallization. Pegmatites contain exceptionally large crystals and they contain rarely minerals than other types of rocks. They have interlocking crystals usually larger than 2.5 cm in size. Generally most Pegmatites are found in sheets of rock that are dikes and veins Also near large masses of igneous rocks called batholiths.

Syenite, any of a category of intrusive igneous rocks basically composed of an alkali feldspar and a ferromagnesian mineral. A unique group of alkali syenites is characterized by the presence of a feldspathoid mineral inclusive of nepheline, leucite, cancrinite, or sodalite (see nepheline syenite). Chemically, syenites comprise a slight amount of silica, incredibly big amounts of alkalies, and alumina. The call become first used by Pliny the Elder.

Granodiorite  is a phaneritic-textured intrusive igneous rock similar to granite, but containing more plagioclase feldspar than orthoclase feldspar. According to the QAPF diagram, granodiorite has a greater than 20% quartz by volume, and between 65% to 90% of the feldspar is plagioclase. A greater amount of plagioclase would designate the rock as tonalite.

An intrusive igneous rock, peridotite is coarsegrained and dense. It is light to dark green in color. Peridotite contains at least 40 percent olivine and some pyroxene. Unlike the olivine grains, the pyroxene grains in peridotite have a visible cleavage when viewed under a hand lens. Peridotite forms much of Earth’s mantle and can occur as nodules that are brought up from the mantle by kimberlite or basalt magmas.

Kimberlite is an igneous rock that major source of diamonds. Kimberlite is a variety of peridotite.  It is rich in mica minerals content and...

Volcanic bomb is pyroclastic rock that is a cooling of a mass of lava it flies thorough the air after eruption. If it is...

Trachyte, light-coloured, very fine-grained extrusive igneous rock that is composed chiefly of alkali feldspar with minor amounts of dark-coloured minerals such as biotite, amphibole, or pyroxene. Compositionally, trachyte is the volcanic equivalent of the plutonic (intrusive) rock syenite. Most trachytes show porphyritic texture in which abundant,