Utah’s “Dirty Diamonds”

Alice Sikorski photo

Alice Sikorski photo

Story by Alice Sikorski

Located in the northern part of Utah, the Great Salt Lake is the largest saltwater lake in the Western Hemisphere. In an average year, the lake covers an area of around 1,700 square miles, but this measurement fluctuates substantially due to its shallowness. For instance, in 1963 it reached its lowest recorded level at 950 square miles, but in 1988 the surface area was at the historic high of 3,300 square miles. In terms of surface area, it is the largest lake in the United States that is not part of the Great Lakes region.

Gypsum occurs on every continent and is the most common of all the sulfate minerals. Gypsum is formed as an evaporative mineral, frequently found in alkaline lake mud, clay beds, evaporated seas, salt flats, salt springs, and caves. The Great Salt Lake has gypsum crystals that have been nicknamed “dirty diamonds”. With a chemical composition of hydrous calcium sulfate (CaSO4 · 2H2O), such crystals are found as floater crystals in clay beds, where they fully form without being attached to matrix. The dirty diamonds are lenticular (lens-shaped) crystals in the monoclinic system, with a shape that resembles a diamond.

For the full article, see the April 2017 issue.



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