SiO2 is an example of this. In a metal, like Fe or Ag, e- are shared, but move freely around other ions, not atached to a specific ion. This gives metals special characterisitcs not found in other atoms. These are termed the rock-forming minerals . This is called the law of constancy of interfacial angles .
Carbon is an example, because it can xlize into graphite or diamond.
They grow from solutions called melts to fill spaces in a rock. This process is similar to how ice grows on a pond. In most of these groups, Fe, Mg, Na, Ca, K, Al combine with the Si and O in varying ratio to form different mineral. Each mineral has its own chemical formula and set of physical properties . We'll discuss these in lab.