what is the practical purpose of miller indices? what is it used for?

Question

If we take a hand specimen of quartz for instance does every face on it have a different form and hence a different miller reference?

Answer 1

The practical purposes are fairly limited but not insignificant. The practical applications come from the fact that the physical and electrical properties of crystals are dependant on crystallographic orientation. This is because the arrangement of atoms is different in different directions. Some practial examples... Aluminum beverage cans are produced from Al alloy sheet that requires a relatively specific crystallographic texture. Otherwise, the sheet does not form a can successfully. Integrated circuit chips (ICs or computer chips) are built on a specific crystallographic plane of single crystal Si. Same is true of LEDs built on single crystal sapphire wafers. Material science is a wonderful thing (if you are in to it).

Answer 2

The most important practical purpose of Miller Indices is to make the people who know how to define and assign them look really smart and make other people just scratch their heads in confusion.
Seriously, I know all about the Miller Indices, but never really understood how such information could be used in a practical manner.