Ask Marilyn ® by Marilyn vos Savant is a column in Parade Magazine, published by PARADE, 711 Third Avenue, New York, NY 10017, USA. According to Parade, Marilyn vos Savant is listed in the "Guinness Book of World Records Hall of Fame" for "Highest IQ."
In her Parade Magazine column of January 26, 1997, Marilyn firmly states that no sand on Hawaiian Island beaches comes from sources outside the islands.
When I was at the King Kamehameha Hotel on the big island of Hawaii we were told that many resorts bring in white sand from California to Hawaii. Not ALL of course, but definitely some. Sorry I can't get a hard reference for this, but I'll bet lots of people write of the error.
Perhaps this is just a myth that Hawaiians like to tell the Mainlanders, or perhaps there's truth to the story.
Joe Cahak <email@example.com> adds:
The black sand does indeed come from the lava. The white sand does indeed come from coral and other crustations, shells etc. The green sand comes from the lava and is the first mineral to crystalize out of the lava. It is easily separated from the remainder of the black lava when it hits the water at a lava outflow and is moved by the wave action to separate by bouancy gradiant (gravity) into a banding of white, green and black sand that exists on some of the beaches of Hawaii. There is a green sand beach on the east side of the South Point of the big island of Hawaii showing this effect very dramatically. I also wish to point out that all the Hawaii beaches contain some amount of white, black and green sand as can be seen if you closely take a look at the sand if you are ever in Hawaii.
My wife and I were on the island of Kauai on Lumahaii Beach on the north side in the spring. The wave action had created a stepped beach front. You could see how the wave action caused a distinct layering of the sand colors. This green and black layers were very discernable. It was quite beatiful as the waves across the shallow water at our feet spread a rainbow of colors across our feet.
I was also told when we stayed on Wakikee beach on the island of Oahu that the beach suffered some damage in a storm. The storm took much of the coral beach sand out to sea and the locals did barge in sand from Southern California. They used it on this beach because of the vacationing population who go to Hawaii to see and use the beach.
Jeff Kaylin <firstname.lastname@example.org> offers another bit of trivia:
When touring the Florida Keys, I was told that all the sandy beaches were man made. Sand was trucked to the Navy base so that sailors could have a sandy beach. It seems that the coral reefs protect the beaches so that typical sand formation does not have a chance.