Igneous Rocks

Lapilli, which means "little stones" in Italian, refers to small rock fragments ejected during volcanic eruptions. These fragments typically range in size from 2...

Phonolite is a type of volcanic rock that belongs to the family of igneous rocks. It is characterized by its unique mineral composition and...

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.

Norite is a type of igneous rock that is primarily composed of the mineral orthopyroxene, along with plagioclase feldspar. It is a mafic rock,...

This volcanic rock is named after the Andes Mountains. Intermediate in silica content, it is usually gray in color and may be fine-grained or porphyritic. Andesite is the volcanic equivalent of diorite. It consists of the plagioclase feldspar minerals andesine and oligoclase, together with one or more dark

Indigo Gabbro, also known as Mystic Merlinite, is a crystal that belongs to the igneous rock family. It is a unique and visually striking...

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)

Tinguaite is a type of volcanic rock, primarily composed of nepheline and alkali feldspar, with lesser amounts of other minerals such as amphibole, biotite,...

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

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.

Basalt is the most common rock on Earth’s surface. Specimens are black in color and weather to dark green or brown. Basalt is rich in iron and magnesium and is mainly composed of olivine, pyroxene, and plagioclase. Most specimens are compact, fine-grained, and glassy. They can also be porphyritic, with phenocrysts of olivine, augite, or plagioclase. Holes left by gas bubbles can give basalt a coarsely porous texture.

Pyroxenite is an ultramafic igneous rock that contain pyroxene group minerals such as augite, diopside, hypersthene, bronzite or enstatite. This is a coarse-grained rock...