Aug 10, 2022 11:36 PM

From the Archives: Selenite “Feathers”

Posted Aug 10, 2022 11:36 PM
Photo courtesy of Don Weiss Photography
Photo courtesy of Don Weiss Photography

By Julie Martineau
For The Burlington Beacon

These objects are probably millions of years old and did not come from the Des Moines County area, although the material that they are made of is found here in abundance.

This "feather” is thought to be made of a type of stone known as selenite and was originally collected by Charles Perkins or one of his family members during one of their many sojourns around the country.

Selenite forms when hydrous calcium sulfate-rich salt water evaporates, leaving behind different types of gypsum. In this case, the “feathers” are harder than normal selenite, which can be scratched with a fingernail.

Des Moines County is home to most of the forms of hydrous calcium sulfate, including gypsum, selenite, and anhydrite, thanks to a rather large lens of the material located just south of Mediapolis. The lens is currently being mined by the US Gypsum Company.

The site was originally discovered by well drillers, who noted a zone of gypsum at greater than 100 feet, which now reaches at least a depth of 616 feet. And, tests show that the mine could go as deep as 700 feet. The mine is the deepest in Iowa and the only mine in Iowa from which Devonian gypsum is mined.

Des Moines County is not the only place in Iowa where gypsum can be found; there is a large bed located near Fort Dodge and Webster City. It can also be found all over the world, in different forms and various qualities and quantities. And while the Fort Dodge mines were discovered first, and are perhaps better known, the Sperry Mine rock is actually older, and the deposit appears to be much larger. It is estimated that the Fort Dodge site will be played out in the next 30 years or so, but the Sperry mine appears to have many decades before the mine is played out.

As for the Perkins family, we are not sure what prompted them to collect the objects, other than it was fashionable for people to collect bits of natural and ethnographic history and show them off in a "cabinet of curiosities."

The Perkins family amassed quite a collection over their time, including some rare minerals and other objects. The collection came to us from the Burlington School District, which originally received the objects directly from the family.

Want to see part of the Perkins Collection? Pieces are on display at the Heritage Museum, located at 501 N. Fourth St. in Burlington.