Why are the blue ridge mountains "blue"?
Does it have to do with the blue colored haze you see when looking at
them? if so, what causes that?
Or is it because of the blue colored rocks? if so, what causes that? 
Are those rocks located only on the ridges?

ncz...

This page from the Dartmouth College Alumni site, containing
Chapter 4 from 'Scenic Driving Virginia' by Bruce Sloane, notes:

"The mountains get their name "Blue Ridge" from their typical
 hazy blue appearance most of the year."

Much more on the page:
http://www.dartmouth.org/classes/57/piedmont.htm


Another site, The Blue Ridge Highlander, is exclusively devoted
to extensive coverage of all things related to the Blue Ridge
Mountain communities. On this page titled, 'The Playground of
the Gods', it says:

"The name "Blue Ridge" was appointed to them by early American
 pioneers due to the blue hue they reflected against the horizon,
 it was later discovered the blue coloring was caused by a chemical
 compound released naturally by pine trees that causes a hazy
 condition that makes the Blue Ridge Mountains appear blue from
 a distance."
http://www.theblueridgehighlander.com/playgrounds_of_the_Gods/index.html


On a blog titled, 'Blue Ridge Muse A writer and photographer
returns home', is a wonderful picture, looking through a pine
forest covered in a mist into the sunrise, which dramatically
shows the resulting blue color in the air:
http://www.blueridgemuse.com/muse2/2005/04/morning_promises.html


Additional information may be found from an exploration of
the links resulting from the Google searches outlined below.

sublime1-ga


Searches done, via Google:

"name blue ridge"
://www.google.com/search?q=%22name+blue+ridge%22

Searches on Google Images:

"blue ridge mountains"
http://images.google.com/images?q=%22blue+ridge+mountains%22

Distant mountains often appear to be blue.  There are Blue Mountains
(so named) in Australia, Oregon/Canada and Jamaica, and probably
elsewhere.