How Tungsten Atoms Came on Earth

6 billion years ago the solar system was formed by condensation, contraction, and subsequent collapse of an interstellar cloud. More than 99% of the matter of the solar system is concentrated in the sun the rest is contained in planets, meteorites, and comets. This event stopped the continuous evolutionary change in element concentrations of the system. Besides hydrogen and helium, the cloud contained the elements formed in exploded stars, as described in Section 2.1. One of the heavier elements in this ash is tungsten. We do not know to how many star cycles this material, or part of it, was subjected. 

BCnowledge about the evolution of the solar system is mainly based on meteorite investigations. With the exception of material brought to earth by spacecrafts from the 

Many meteorites have never been subjected to processes of planetary differentiation. These imdifferentiated meteorites come fix m planetesimals that were never molten and resemble die composition of the solar nebula at the time and place of their formation. They exhibit approximately solar system composition, are called chondritic meteorites, and represent one big group of meteorites. The second group consists of the differentiated meteorites which represent pieces of partially or totally molten parent bodies. Examples of this group are meteoritic basalts (eucrites) or iron meteorites. The latter are pieces of the segregated core of the parent body. 

The partly oxidizing conditions during core segregation in the earth evolution are responsible for the fact that we find tungsten deposits in the crust. 

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