Help Finding and Identifying Local stones

I'm new to rockhounding and all that good stuff(i have done it before though, i'm not THAT new), and i found what appears to be a good place to look. I live in california, in the foothills of Mt. Baldy, and i found that a local stream (etiwanda falls if anybody is in the area) has some shiny stones in it. Most of them are blue-green, but some are purple or silver colored. I need some info on how to find bigger chunks, techniques, recommended nearby locations, and what stones I am looking at, cause I am clueless. Oh, and if it helps, I found that by hiking another 20 minutes upstream, this is an underground stream. Actually, I'm sure that helps. Don't know why I didn't mention it earlier. Thanks in advance! 

JC, best advice I can give is check the local phone book and find a rock shop in your area...check the net and see if there are any clubs in your locale...hope this helps

When I went to New Mexico to rock hound I bought a book, Gem Trails of New Mexico.  There's a S. CA version as well...it's a handy guide for a relative newbie:)

http://www.desertusa.com/web_cart/db/pages/5133.html

Thanks vibes, I actually just found that book maybe a half and hour ago after a suggestion by dustcap. It's a really good find!