What silicate mineral is the basic building block of many rocks?
1 Answer
Feldspar (a silicate containing aluminum, calcium, and alkali metals) is the most common of many silicate minerals in our crust.
Explanation:
Along with feldspar we have olivine (a magnesium-iron silicate), which is very common in the mantle and can mix into the crust through tectonic movements and volcanic action. However, olivine weathers quickly on the Earth's surface.
Silicates are common in our rocks because silicates are what is there. Oxygen and silicon, in that order, are the most common elements in Earth's crust and mantle. These elements combine with metals to form silicates.
It's not just Earth. Silicates are the prime constituents of rocky matter everywhere in the Solar System, and likely beyond. This chemistry gets traced back to the composition of the original nebula from which the Sun and planets formed, which in turn came from other stars that lived and died before our Sun came into being.
It ultimately goes back to oxygen and silicon having relatively favorable routes for stellar nucleosynthesis. In http://chemwiki.ucdavis.edu/Core/Physical_Chemistry/Nuclear_Chemistry/Nucleosynthesis%3A_The_Origin_of_the_Elements the relative abundances of various elements in the Earth and the Universe are listed.
From this source we see that oxygen and silicon are relatively abundant both here and out there. So are magnesium, aluminum, calcium and iron -- the metals that combine with oxygen and silicon to form most of the silicates in our rocks.
