The smaller size of the yttrium group allows it a greater solid solubility in the rock-forming minerals that comprise Earth's mantle, and thus yttrium and the yttrium earths show less enrichment in Earth's crust relative to chondritic abundance, than does cerium and the cerium earths.
32.
The researchers found that the fragments from the crater zone had a chondritic texture and the following mineral composition : pyroxene ( 1 ) 40 %, olivine 20 %, feldspar 10 %, pyroxene ( 2 ) 10 %; kamacite 15 %, troilite 5 %, and traces of chromite and native copper.
33.
INGEMMET ( " Instituto Geol�gico Minero y Metal�rgico " ) of Peru released in September 2007 an analysis which showed that the fragments from the meteorite had a chondritic texture and a mineral composition of pyroxene ( 1 ) 40 %, olivine 20 %, feldspar 10 %, pyroxene ( 2 ) 10 %; kamacite 15 %, troilite 5 %, and traces of chromite and native copper.
34.
One of the authors, Owen Toon notes : " In this new scenario, organics can be produced efficiently in the early atmosphere, leading us back to the organic-rich soup-in-the-ocean concept . . . I think this study makes the experiments by Miller and others relevant again . " Outgassing calculations using a chondritic model for the early earth complement the Waterloo / Colorado results in re-establishing the importance of the Miller Urey experiment.
35.
Using the chondritic reference model and combining known compositions of the mantle, the unknown component, the composition of the inner and outer core, can be determined; 85 % Fe, 5 % Ni, 0.9 % Cr, 0.25 % Co, and all other refractory metals at very low concentration . and a 4 5 % weight deficit for the inner core; which is attributed to lighter elements that should be cosmically abundant and are iron-soluble; H, O, C, S, P, and Si.
36.
Because chondrites accumulated from material that formed very early in the history of the solar system, and because chondritic asteroids did not melt, they have very primitive compositions . " Primitive, " in this sense, means that the abundances of most chemical elements do not differ greatly from those that are measured by spectroscopic methods in the photosphere of the sun, which in turn should be well-representative of the entire solar system ( note : to make such a comparison between a gaseous object like the sun and a rock like a chondrite, scientists choose one rock-forming element, such as silicon, to use as a reference point, and then compare ratios.
