Was there a sun in the asteroid belt 200 million years ago? http://2sun.cc/full.htm The Earth's Mantle -- QUOTE: "Earth has the same recipe of elements as the Sun and the other planets (ignoring hydrogen and helium, which have escaped Earth's gravity). Subtracting the iron in the core, we can calculate that the mantle is a mix of magnesium, silicon, iron, and oxygen that roughly matches the composition of garnet. But exactly what mix of minerals is present at a given depth [inside the mantle] is an intricate question that is not firmly settled."http://geology.about.com/od/mantle/tp/mantleintro.htmIf the metallic materials are not originally from the earth, is there a way to put them inside the mantle, other than opening an area in the crust, with a depth that reaches the mantle, and then place them there?

http://m.phys.org/news/2014-02-life-wrong.html