Good stone and mineral info is in my free gem index at Rings & Things Gem Index. Another resource is www.mindat.org. Searching with google you can find good info if you follow the stone name with the word "mineral." This eliminates a lot of sites selling beads or jewelry made with the stone. For example, google "turquoise mineral" finds lots of info about the stone turquoise.
Here are a few resource names. If I had the web and addresses available I added them. The rest you can find with google.
Manufacturing Jewelers and Silversmiths of America (MJSA) 45 Royal Little Drive, Providence, RI 02904
Phone: 1-401-274-3840 | Toll-free: 1-800-444-6572 | Fax: 1-401-274-0265
E-mail: info@mjsa.org | Web site: www.mjsa.org
Fashion Jewelry Trade Association
AGTA - American Gem Trade Association http://www.agta.org/
IACA - Indian Arts and Crafts Association
http://tech.groups.yahoo.com/group/americanturquoisemines/
http://www.yourgemologist.com/ISGForumsBoard/index.php
http://gemologyonline.com/Forum/phpBB2/index.php
JA - Jeweler's of America
Hong Kong Gemstone Manufacturers Association or the Hong Kong Pearl Association
http://www.americanpearl.com/ has an "education " section with some good information
If I can give you more specific info about particular stones or other types of associations, please ask.