Gems Found in Wisconsin

Agate is commonly found along the Lake Superior shore.
••• Hemera Technologies/ Images

The geology of Wisconsin does not lend itself to a lot of precious gemstones or even nugget gold, but during the 1800s residents unearthed diamonds in areas of moraines – glacial deposits – near southeastern Wisconsin. The largest of these diamonds, the Theresa diamond, discovered in 1888 close to the Green Lake Moraine near Kohlsville in Washington County, weighed 21.5 carats and ended up cut into 10 separate stones by its owner. A gem is essentially any mineral, rock or petrified mineral a jeweler can cut or facet and polish for a jewelry setting. Traditionally, precious gemstones include diamonds, sapphires, rubies and emeralds, while all other gemstones fall under the category of semi-precious.

TL;DR (Too Long; Didn't Read)

Diamonds found in Wisconsin occur in glacial deposits and alongside streams and rivers in gravel beds. The glaciers ground up most of the gold into fine, flour gold deposits scattered in stream and riverbeds.

Madison Diamonds

Madison diamonds, named for these precious gems found in Dade, Waukesha and Washington counties include the infamous Eagle diamond and the Theresa diamond. The Eagle diamond from Waukesha County, heisted from New York's American Museum of Natural History in 1964 and discovered by a farmer, weighed 16.25 carats when found. Kenosha County is home to many smaller diamonds, with the discovery of a diamond-bearing lamprophyre diatreme – a volcanic-type tube housing diamond-bearing igneous rock or kimberlite – covering close to 50 acres.

Wisconsin Gold

Placer gold is rare in Wisconsin because most of the gold in the area was crushed into fine flour-type gold during the glacial movement that helped to form the Great Lakes. The best places to find flour gold include areas of already discovered gold like Ashland, Bayfield, Clarke, Dane, Douglas, Dunn and other counties as listed by the University of Wisconsin (see References). Placer gold, found in streams and having rounded edges, comes from placer deposits or gold veins exposed because of erosion. This washes the placer nuggets into streams and rivers for gold-panners to find. You might find small bits of placer gold in Polk County, lodged in sediment and rocks, when rivers and streams run low.

Minerals and Semi-Precious Gems of Wisconsin

You can find Wisconsin quartz in multiple counties in Wisconsin, along with other minerals including andalusite, azurite, beryl, calcite, celestine and many more. You can also find Lake Superior Agate in select areas of Wisconsin, close to deposits near the River Falls in St. Croix County.

Related Articles

Where to Rock Hunt Gems in Idaho
Gems Found in Colorado
Rock Hunting In Alabama
Gem Hunting in Canada
How Is Quartz Extracted?
In What Rock Formations Can Gold Be Found?
How to Mine Rose Quartz & Gold
Places to Dig for Gems
How to Find Geodes in Idaho
How to Test and Find Raw Diamonds
Rock Crystals Found in Tennessee
How to Test a Rock for Gold
What Natural Gemstones Are Organic to Vermont?
What Precious Gems Can Be Found in Texas?
What is a Sardonyx?
How Do I Polish Sliced Agate?
What Equipment to Take on a Gem Mining Trip
How to Find Agates
Gems Native to Connecticut

Dont Go!

We Have More Great Sciencing Articles!