Chemical structure of Turquoise
I don’t know how to read or make sense of this: $\ce{CuAl6(PO4)4(OH)8.4H2O}$ the chemical formula of turquoise.


It means for every atom of copper (Cu), there are 6 atoms of aluminum, 4 phosphate groups (which each contain a phosphate atom and four oxygen atoms), 4 hydroxide groups (which each contain an oxygen and a hydrogen atom) and 4 waters (which each contain two hydrogen atoms and one oxygen atom). So the parentheses are for grouping, and the numbers are to count how many atoms or groups there are.

The structure is a crystal, so it goes on and on in all directions. That is why I was careful to say "for every atom of copper...". For other substance like carbon dioxide that are found as molecules, it is less complicated (there, the formula actually tells you the number and kind of atoms in a single molecule).


  Chemical structure of Turquoise


Some of the components in turquoise are positively charged (copper and aluminum) and some are negatively charged (hydroxide and phosphate). The building blocks are arranged that positive and negative come close together, and like charges are further apart. The entire structure is very complicated. 

The picture below does not show all the atoms, but instead shows copper, aluminum and phosphate as 3D shapes (the metals and the phosphorus would be in the center of each of the shapes). The shapes have common corners occupied by oxygen atoms (in the formula, these appear as part of phosphate, hydroxide and water). The hydrogen atoms are shown at tiny spheres.

Source: http://rruff.info/uploads/MM64_905.pdf