Theories of gravitation. Couprie, Dirk L. Heaven and Earth in Ancient Greek Cosmology: from Thales to Heraclides Ponticus.

• • • • • • • • Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, evolution, distribution, identification and taxonomy.[1] Modern biology is a vast and eclectic field, composed of many branches and subdisciplines.[clarification needed] However, despite the broad scope of biology, there are certain general and unifying concepts within it that govern all study and research, consolidating it into single, coherent field. In general, biology recognizes the cell as the basic unit of life, genes as the basic unit of heredity, and evolution as the engine that propels the synthesis and creation of new species.

It is also understood today that all the organisms survive by consuming and transforming energy and by regulating their internal environment to maintain a stable and vital condition known as homeostasis.

Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of rock-forming minerals and make up approximately 90 percent of the Earth's crust. They are classified based on the structure of their silicate groups, which contain different ratios of silicon and oxygen. Lawsonite is a hydrous calcium aluminium sorosilicate mineral with formula CaAl2Si2O7(OH)2H2O. Lawsonite crystallizes in the orthorhombic system in prismatic, often tabular crystals.

Crystal twinning is common. It forms transparent to translucent colorless, white, and bluish to pinkish grey glassy to greasy crystals. Refractive indices are n? Filme Outlander Guerreiro Vs Predador Dublado Online there. =1.665, n?=1.672 - 1.676, and n?=1.684 - 1.686. It is typically almost colorless in thin section, but some lawsonite is pleochroic from colorless to pale yellow to pale blue, depending on orientation. The mineral has a Mohs hardness of 8 and a specific gravity of 3.09. It has perfect cleavage in two directions and a brittle fracture. Ilvaite is a sorosilicate of iron and calcium with formula: CaFe2+2Fe3+Si2O7O(OH).

Both manganese and magnesium substitute in the structure. Ilvaite crystallizes in the monoclinic system in black prismatic crystals and columnar masses. It is black to brownish black to gray and opaque. It has a Mohs hardness of 5.5 to 6 and a specific gravity of 3.8 to 4.1.

Ilvaite is structurally related to lawsonite. It occurs in contact metamorphic rocks and skarn ore deposits. It also occurs less commonly in syenites. Ilvaite was first described in 1811 on the island of Elba and the name ilvaite from the Latin name ilva of the island.

Sometimes referred to as yenite. Commonly encountered species and varieties: Schorl species: Brownish black to black—schorl Dravite species: from the Drave district of Carinthia Dark yellow to brownish black—dravite Elbaite species: named after the island of Elba, Italy Red or pinkish-red—rubellite variety Light blue to bluish green—Brazilian indicolite variety (from indigo) Green—verdelite or Brazilian emerald variety Enstatite is a mineral; the magnesium endmember of the pyroxene silicate mineral series enstatite (MgSiO3) - ferrosilite (FeSiO3). The magnesium rich members of the solid solution series are common rock-forming minerals found in igneous and metamorphic rocks. The intermediate composition, (Mg,Fe)SiO3, has historically been known as hypersthene, although this name has been formally abandoned and replaced by orthopyroxene. When determined petrographically or chemically the composition is given as relative proportions of enstatite (En) and ferrosilite Monoclinic cummingtonite is compositionally similar and polymorphic with orthorhombic anthophyllite, which is a much more common form of magnesium-rich amphibole, the latter being metastable. Cummingtonite shares few compositional similarities with alkali amphiboles such as arfvedsonite, glaucophane-riebeckite. There is little solubility between these minerals due to different crystal habit and inability of substitution between alkali elements and ferro-magnesian elements within the amphibole structure.