It is a pleasure to acknowledge the aid of many interested people who greatly facilitated the NGS by friendly cooperation, encouragement, and suggestions. Discussions of ideas and helpful criticisms were generously made at various stages by numerous individuals from within the USGS, other federal agencies, state agencies, academia, industry, and colleagues from other nations.

Within the USGS we are indebted to the Mineral Resources Program Council, the Surveys & Analysis Project chiefs (Suzanne Nicholson, Doug Stoeser, Ric Wilson, Steve Ludington, Dave Piper), chemists, geochemists, geologists, GIS specialists, and many others including Stephen Wilson, Elizabeth Bailey, Bill Cannon, Gordon Haxel, Bruce Johnson, Greg Lee, Tom Light, Steve Smith, Dave Smith, Mike Zientek, Noel Burkhead, Jim McNeal, Wendy Speckman, Jim Herring, Jim Crock, Charlie Severson, Paul Schruben, Dave Sutphin, John Jackson, William Heran, Wendy Fife Jim Vecchioli, Chuck Holmes, Frank Dulong, Chris Murphy, Dave Detra, Joe Taggart, Roy Knight, Paul Lamothe, Rich O’Leary, Jim Budahn, Matthew Dombroski, Jason Willett, Margaret Perry, and Ed Oaksford. Special appreciation is extended to Mineral Resources Team Chief Scientists Joe Duval, Klaus Schulz, Art Schultz and Ed du Bray for their continued support and interest.

From other agencies, the NGS was stimulated by the participation of Rufus Chaney (USDA), Darryl Leach (NRCS), David Hopkins (NDSU), Mike Ulmer (USDA-NRCS), and Wendell A. (Bud) Norvell (USDA Plant, Soil & Nutrition Lab.)

Special appreciation is also extended to state geological surveys participating in sample collection campaigns in areas where new samples were acquired by virtue of their collaboration. The collaborating State agencies (in alphabetical order) and their participating geologists, engineers, or scientists: Geological Survey of Alabama: Mirza Beg, Lewis Dean, Andrew Rindsberg, Stephen Klimetz, Blakeney Gillett, Richard Hummell, Arthur Mc Lin, III, Berry H. (Nick) Tew, Jeff Natharius, and Bob Meintzer; Arkansas Geological Commission: Mac Woodward, Bekki White, J. Michael Howard, Bill Shelton; California Geological Survey: Ron Churchill, Jim Davis; Florida Geological Survey: Walt Schmidt, Steve Spencer, Jackie Lloyd, Spencer Mitchell, Rodney Dehan; Georgia Geologic Survey: Mark Cocker, Earl Shapiro, Joseph Summerour, R. Benton, Xiabing Chen, Alan Fizer, Robert Ringer, Sean Rhett, Ken Scandrett, Bill Slocumb, Frank Van Arsdale, and Steve White; Illinois State Geological Survey: Bill Shilts, James Risatti, David Westermann; Indiana Geological Survey: John Steinmetz, Nelson Shaffer, Amzie Wenning, Maude Dewees; Iowa Geological Survey: Jim Giglierano, Bob Rowden, Bob Libra, Loretto Stambuk, Bernie Hoyer; Louisiana Geological Survey: Riley Milner, John Chacko, and Syed Haque; Michigan Department of Environmental Quality: Kevin Kincare; Mississippi Department of Environmental Quality: Cragin Knox and David Thompson; North Dakota Geological Survey: Lorraine Manz, John Bluemle; Ohio Geological Survey: Thomas Berg, Dennis Hull, Ron Rea, Bob Van Horn; Oregon Department of Geology and Mineral Industries: Ian Madin, Vicki McConnell, Ron Geitgey; South Carolina Geological Survey: Bill Clendenin, Arthur “Butch” Maybin, Jr., Will Doar III, Ralph Willoughby, and Gary Taylor; South Dakota Geological Survey: Derric Iles, Jay Gilbertson; Texas Bureau of Economic Geology: Jay Raney; Washington State Department of Natural Resources: Ron Teissere.

We are also indebted to the contributions of the following corporate geologists and collaborators: Jeffrey Foley and Robert "Nick" Enos (Calista Corporation); Jack "Alligator" Moores (Bristol Bay Native Corporation); Bill Ellis (Alaska Earth Sciences); Kerry Stanaway (Rio Tinto Iron & Titanium); and industry geologists and technicians: Daniel Cordier, Roger McLimans, Donny Wilkerson, Miguel Garcia, Alex Montalvo, Kelly Boatwright, Pam Mason, and Howard Bartlett.