Geochemistry Lecture 5 Strc, Comp of Meteorites скачать в хорошем качестве

Geochemistry Lecture 5 Strc, Comp of Meteorites

A Meteorite is a piece of rock from outer space that strikes the surface of the Earth. Any extra-terrestrial material hitting the Earth. A Meteoroid is a meteorite before it hits the surface of the Earth. Meteors are glowing fragments of rock matter from outside the Earth's atmosphere that burn and glow upon entering the Earth's atmosphere. There are four meteorite types; aerolites, siderolites, siderites, and tektites. Stony meteorites (Aerolites) Consisting of 90% silicate minerals and 10% Fe-Ni alloy. Stony meteorites can be classified as chondrites and achondrites. On the basis of texture the Aerolites or stones are divided into two groups Chondrites & Achondrites. The Siderolites or stony-Iron meteorites made up of Ni-Fe & silicates in equal concentration. Siderolites are further classified as Pallasites and mesosiderites based on the base of nickel-Iron enclosing grains of olivine & pyroxene. Siderites consists of One or two nickel-metallic phases and Accessory Troilite (FeS) & graphite;Daubreelite (FeCr2S4); One or two nickel-metallic phases . Metal generally shows a definite structure known as Widmanstatten pattern. Tektites are gravel-sized bodies composed of black, green, brown or grey natural glass formed from terrestrial debris ejected during meteorite impacts. superficially similar to some terrestrial volcanic glasses (obsidians).