Minerals

A mineral is a naturally occurring solid, homogeneous substance with a definite chemical composition, and have a specific crystalline structure, a highly ordered atomic structure, and specific physical properties, formed through geological processes.
A rock is an aggregate of one or more minerals. Some rocks are predominantly composed of just one mineral. Other rocks contain many minerals, and the specific minerals in a rock can vary widely.. The vast majority of the rocks of the Earth's crust consist of quartz, feldspar, mica, chlorite, kaolin, calcite, epidote, olivine, augite, hornblende, magnetite, hematite, limonite and a few other minerals.
A main determining factor in the formation of minerals in a rock mass is the chemical composition of the mass, for a certain mineral can be formed only when the necessary elements are present in the rock.
Every year, almost 2000 minerals are discovered. Two types of minerals are usually found by the researchers based on their chemical components. In fact, only a few dozen are common within the rocks of the Earth's crust so it is only a limited number of minerals that you are likely to find in your backyard.
There are many different types of minerals and each type is made of particular types of atoms. The atoms are bonded together and arranged in a special way called a crystal lattice, a network of atoms. The lattice of atoms is what gives a mineral its crystal shape.
Minerals are needed by the body in small amounts to help it function properly and stay strong. Iron, calcium, potassium, and sodium are some of essential minerals. Humans need small amounts of about 14 minerals to maintain normal body function and good health. Read More

Andesite

Andesite is common in most of the world's volcanic areas. Andesites occur mainly as surface deposits and, to a lesser extent, as dikes and small plugs.
Andesite is an igneous, volcanic rock, of intermediate composition, with most commonly is fine-grained, usually aphanitic to porphyritic texture. The mineral assembly is typically dominated by plagioclase plus pyoxene and/or hornblende. biotite, quartz, magnetite, sphene are common accessory minerals. Alkali feldspar may be present in minor amounts. The quartz-feldspar abundances in andesite and other volcanic rocks are illustrated in QAPF diagrams. Relative alkali and silica contents are illustrated in TAS diagrams.
Classification may be refined according to the most abundant phenocryst. If hornblende is the principal accessory mineral name is hornblende-phyric andesite
Andesite porphyritic. In composition, andesites correspond roughly to the intrusive igneous rock diorite and consist essentially of andesine (a plagioclase feldspar) and one or more ferromagnesian minerals, usually amphibole or biotite. The larger crystals of feldspar and ferromagnesian minerals are often visible to the naked eye; they lie in a finer groundmass, usually crystalline, but sometimes glassy. There are three subdivisions of this rock family: the quartz-bearing andesites, or dacites, sometimes considered to be a separate family; the hornblende- and biotite-andesites; and the pyroxene-andesites.
Andesites are typically medium gray and porphyritic, with phenocrysts of white to light gray plagioclase and/or black augite, hornblende, and/or biotite. Some andesites are reddish and some are vesicular. If you find quartz, you are probably looking at a rhyolite.
Andesite
- can be considered as the extrusive equivalent to plutonic diorite.
- are characteristic of subduction tectonic environments in active oceanic margins.
- forms at convergent plate margins and is thought to be the product of partial melts of the water-rich subducting oceanic crustal basalts or of the intervening wedge of lower crustal rocks above the subducting plate
- is formed at accretionary plate margins Read More