Gypsum & Alabaster

Old Off Shore Alabaster Loading facility, photo by hz536n/George Thomas

One of the neatest features for me about Michigan in Pictures are the many things I learn from the photos that are posted. Today’s photo of the Lake Huron loading platform for US Gypsum is a perfect example. The Iosco County Historical Society explains that:

The tramway of the U. S. Gypsum Company at Alabaster has long been a tourist attraction. Built in 1928 the tramway stretches 1.3 miles out into Saginaw Bay. Like a horizontal ski-lift, the cable system carries 72 “buckets” of gypsum to a waiting ship or to the storage bin. Each bucket holds more than two tons. The tramway includes 6,450 feet of one and three-quarter inch steel cable and 14,000 feet of three-quarter inch cable. At a length of 6,350 feet it is the longest over-water bucket tramway in the world.

…Until 1898 when the railroad spur was installed, all shipments were made by sailing vessels that tied up to a 600 foot dock. Marine shipments were resumed in 1929 after the building of the tramway enabled the larger ships to load in deeper water at the end of the tramway. Rail shipments were then made when the boat season was closed.

The tramway was dismantled (though concrete pads which may house wind turbines remain). You can also read an interesting account detailing the history of the town of Alabaster. While I knew that gypsum was used in drywall, I had no idea of its versatility (or Michigan’s status as a leading gypsum producer). You can learn about in great detail from MSU Geology’s page on gypsum:

If you were given a chance to win a jackpot by correctly naming a material that was used in the pyramids and in your toothpaste; that helps peanuts grow and makes movie snow; and that is used in mushroom beds and the walls of your house, chances are at least 100 to 1 that the quizmaster would holler “Sorry, your time is up,” before you could say “hydrous calcium sulphate.”

But, don’t feel badly.

Even though more than 12 1/2 million tons of gypsum were used in the USA last year, and even though the average person is surrounded by gypsum products from dawn to dusk, from the cradle to the grave, people do not know much about gypsum.

Gypsum can be ground up and “boiled” (calcined) at a comparatively low temperature until 75% of its moisture content has evaporated. When that happens, the rock becomes a fine powder, commonly known as Plaster of Paris. By returning the water to the powder, one can make a pliable mortar that can be formed into any shape and hardened. Gypsum is the only natural substance that can be restored to its original rock-like state by the addition of water alone.

Check this photo out background big and see more in George’s Fall 2009 slideshow.