Name and draw one example for each of the following types of ...

[ahriuashd]

Name and draw one example for each of the following types of tetrahedra: isolated tetrahedra, single
  chain tetrahedra, double chain tetrahedra, sheet tetrahedra, and framework tetrahedra What will be an ideal response?

Question 2

Why do some minerals have a fixed chemical composition and some have a range of compositions?
  Give an example of a mineral with a range of compositions. What will be an ideal response?

[jesse.fleming]

Answer to Question 1

Olivine, pyroxene, amphibole, biotite/muscovite/mica/clay, quartz/feldspar.

Answer to Question 2

In many minerals, the chemical composition does not vary. In some minerals, one element can
substitute for another if the atoms of the two elements are nearly the same size and the same charge. In
olivine, magnesium and iron can both fill the cation position, so the chemical composition for the
mineral is (Mg, Fe) 2SiO4.

[ahriuashd]

Thanks for the timely response, appreciate it

[JaynaD87]

Excellent