Friday, May 29, 2020

Aragonite worth billions is being mined in The Bahamas.

Article first published in Sports Illustrated, July 6, 1970

Ocean Cay aragonite mining (image)

By Coles Phinizy

Of all the 3,000 islands and islets and cays in the Bahamas, Ocean Cay is the least lovely. It is a flat, roughly rectangular island which, when completed, will be 200 acres and will resemble a barren swatch of the Sahara. Ocean Cay does not need allure. It is being dredged up from the seabed by the Dillingham Corporation of Hawaii for an explicit purpose that will surely repel more tourists than it will attract. In simplest terms, Ocean Cay is a big sandpile on which the Dillingham Corporation will pile more sand that it will subsequently sell on the U.S. mainland.

The sand that Dillingham is dredging is a specific form of calcium carbonate called aragonite, which is used primarily in the manufacture of cement and as a soil neutralizer. For the past 5,000 years or so, with the flood of the tide, waters from the deep have moved over the Bahamian shallows, usually warming them in the process so that some of the calcium carbonate in solution precipitated out. As a consequence, today along edges of the Great Bahama Bank there are broad drifts, long bars and curving barchans of pure aragonite.

Limestone, the prime source of calcium carbonate, must be quarried, crushed and recrushed, and in some instances refined before it can be utilized. By contrast, the aragonite of the Bahamian shallows is loose and shifty stuff, easily sucked up by a hydraulic dredge from a depth of one or two fathoms. The largest granules in the Bahamian drifts are little more than a millimeter in diameter. Because of its fineness and purity, the Bahamian aragonite can be used, agriculturally or industrially, without much fuss and bother.  Read more >>