Oxygen magnesium

The first few decades of space exploration went by without any MS better than m/Am 4 because understanding the solar wind flow, its density, its pressure, or its temperature did not require mass resolution. Not until 1984 did a space MS fly with a resolution of about 10 [10], and it was 1994 before that increased to 100 [11], Suddenly for the first time, the solar wind isotopes of carbon, oxygen, magnesium, silicon, and iron were known, and the models could be tested. Even then, space MS had difficulty measuring rare isotopes, so that it wasn t until 2005 that solar wind samples were returned to Earth inside ultra-pure silicon wafers (the ill-fated Genesis mission [12]) to determine the important triple ratios of ieO 170 lsO. 

Even nuclei, and in particular the class of a nuclei (oxygen, magnesium, silicon, calcium), are the basic products of nucleosynthesis in high-mass stars. They are abundantly present in the ashes of SNll events, where the cx/iron ratio is about three times the solar value. The amounts of even elements ejected by explosion of a high-mass star are, to the first approximation, independent of the star s initial metallicity. 

The major-element compositions of 200 chondritic IDPs were measured by EDS (Table 1 and Figure 12). All of the particles were identified as extraterrestrial because they have approximately chondritic compositions or consist predominantly of a single mineral grain like forsterite or pyrrhotite (commonly found within chondritic IDPs) 37% of the particles are CSIDPs, 45% are CP IDPs, and 18% IDPs composed predominantly of a single mineral. Table 1 summarizes the compositions of the IDPs. Within a factor of 2 the abundances of oxygen, magnesium, aluminum, sulfur, calcium, chromium, manganese, iron, and nickel are approximately chondritic. CP IDPs are a closer match to Cl carbonaceous chondrites than CS IDPs, and they are closer to Cl bulk than to Cl... 

Silicon never occurs as a free element in nature. It always occurs as a compound with oxygen, magnesium, calcium, phosphorus, or other elements. The most common minerals are those that contain silicon dioxide in one form or another. These minerals are known as silicates. 

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