Someone told me the white sand on Florida beaches is not really sand, that it is brought in and dumped there as well as the white sands in New Mexico…..Is this true?
To answer this question it would be a good idea to first understand what sand is! Sand is simply a mineral particle of a certain size. It can be as large as 2 mm (0.07 inches) to as small as 0.05 mm (0.001 inches). If that does not help, then think of a sand particle being about the size of a grain of cayenne pepper to the width of a nickel.
Many beaches in Florida are made up of white sand, as are the white sands of New Mexico. Yet, both of these are white for different reasons.
Florida’s beaches are made up of a mineral called quartz, which gives the sand its characteristic color. Quartz is a very hard mineral that is resistant to weathering. After much physical and chemical weathering over thousands of years, the other minerals that were originally in that location have been lost. Only quartz (and a few other very hard minerals) are left. This gives Florida beaches its white color.
The White Sands area of New Mexico is very different from the Florida beaches. This area was once a shallow inland sea where the mineral, gypsum (calcium sulfate), was carried into this sea by runoff from the local mountains and deposited. This created 275 square miles of the largest gypsum sand dune in the world. Gypsum is white, hence the color of the White Sands of New Mexico. Gypsum also does not absorb heat as much as quartz does, so you can easily walk at White Sands with bare feet under the hot sun. Don’t try this on a quartz sand beach on a hot Florida afternoon!
Are they dumping white sand on Florida beaches? Sometimes, yes, it is necessary. Sea levels are rising, and beaches are susceptible to erosion from storms. So, the State of Florida issues permits for beach “nourishment” when needed. If enough sand has eroded away, local sand is imported to keep the integrity of the beach – and the economy – safe for everyone. For New Mexico, we are not aware of any human-assisted sand replenishment of these dunes where new gypsum is trucked in.
As an added bonus to this answer: sand does not have to be white! In fact there are beaches around the world that are pink, violet, olive green, red, orange, black, grey and multicolored. The color of each sand beach depends on the rock material from which it is weathered and its mineral content. Pink beaches get their color from coral fragments and shells. Violet beaches are dominated by the mineral manganese garnet. Red beaches tend to be derived from lava rocks and volcanic cinder. Green beaches have the mineral, olivine, to give it that color; and the orange beaches of the Maltese Islands are high in iron or, in Sardinia, are developed from orange limestone and shells.
If you want to see more about the color of beach sand, check out this website: http://www.businessinsider.com/colorful-sand-beaches-around-the-world-2015-6
By Nick Comerford, University of Florida