UW Geology Museum

06/01/2026

We love rainbows, and one of our favorites today’s Mineral Monday subject, labradorite! Labradorite is a plagioclase feldspar that sits towards the Ca-rich end of the spectrum, found in mafic rocks such as gabbro and basalt. It is most famous for labradorescence, its namesake optical effect.

Labradorescence is a rainbow shimmer effect caused by long, thin formations called “exsolution lamellae” in crystals of labradorite and similar feldspars. Because the composition of labradorite is not stable as a solid mineral, it deposits as two separate compositions making up lamellae. When these lamellae are the right width, they interact with light waves to make the rainbow shine the mineral is known and loved for.

Labradorite is one of Earth’s most beautiful rainbows. Look for it next time you see a piece of gabbro!

📷 Labradorite, Labrador, Canada. Donated by Peter Duehr.

05/29/2026

We're celebrating wrapping up this season of new beginnings by highlighting a final "Spring Starter"; special specimens that evoke new beginnings over Earth’s history!

Our last Spring Starter is Captorhinus aguti, an early, hook-nosed tetrapod that roamed the supercontinent Pangea between 300 and 250 million years ago. When Pangea broke up, it took C. aguti fossils with it, everywhere from Texas to China! C. aguti sports many traits seen in modern creatures, such as a quadrupedal gait, scaly skin, and a triangular skull similar to those seen in reptiles. They also had more mammalian traits, such as the foot splay that allow primates to walk upright. The genus Captorhinus might also have been the first to develop caudal autonomy, or the ability to sever an appendage like a tail for defense.

Being such an old and widespread species has led to some debate about the relationships between C. aguti and more modern species. They have been theorized to be primitive reptiles, the ancestors to turtles, or, most recently, as relatives to early amniotes. Many of these new hypotheses have come as new fossils and species are found, revealing more traits in C. aguti that lead scientists to revise old models.

The Permian Period was a time of major changes, from the collapse of the Carboniferous rainforests and the breakup of Pangea to the apocalyptic P-T mass extinction event that ended it. It was always unlikely that this species itself would survive until modern day, but they provide information that help us understand the evolution of species we do have now. Swing by the exhibits and look for this special creature on its perch.

Photo 1📷 - Captorhinus aguti fossil, prepared by Chris Pladziewicz, 1993.

05/28/2026

Today we are celebrating tour guide and recent Geological Engineering graduate Mariel! Originally from Menomonee Falls, WI, Mariel has spent the last two years giving tours at the Museum, and her favorite part is the enthusiasm that people show when they ask in-depth questions on tour that allow her to dive beneath the surface level – just like her favorite specimen, the Platecarpus! When not giving tours, Mariel likes to take rides on her longboard.

Post-graduation, Mariel is looking for an entry-level engineering position outside the Midwest. One of her goals is to stay connected to earth science in the role she takes. We wish her the best in her future endeavors!

05/27/2026

Today we are celebrating tour guide and tour coordinator Anna! Anna is originally from Oregon, WI, and has recently graduated with her B.S. in Environmental Science and History. Anna’s favorite specimen in the museum is the Platecarpus, which she attributes to its interesting story. She thinks being a tour guide is a rewarding experience, and she love teaching people and meeting people from all over who want to learn about geology. In that vein, last summer she gave Governor Evers a tour of a bog while she was working at a nature center in northern Wisconsin!

In September, Anna will start her Master’s in Environmental Education at the University of Minnesota Duluth. While there, she will work in developing education programs for the Voyageurs Conservancy. We wish her the best as she continues to inspire young minds!

05/22/2026

As we wrap up the spring season, we're celebrating this season of new beginnings, and highlighting some Spring Starters; specimens that evoke new beginnings over Earth’s history.

This Spring Starter is one you might have heard of before. Archaeopteryx originally gained fame when it was found just a few years after Charles Darwin published On the Origin of Species. It is heralded as an example of a transition fossil, exhibiting traits of dinosaurs and birds.

With new technologies for examining fossils, scientists are continuing to learn about these creatures and their place in the evolutionary tree of life. For example, scientists at Chicago’s Field Museum Archaeopteryx have used CT scans and UV light on their Archaeopteryx specimens to reveal soft tissue details, including scales on the bottom of the creature's toes and bumps on the roof of its mouth. Their research into the fossil’s feathers leads them to claim that Archaeopteryx could indeed fly, but likely in short bursts, similar to a chicken.

Despite being known for over 160 years, new techniques keep shedding new light on old fossils. Swing by the museum and take a peek at this flying pioneer!

Photo 📷 - Archaeopteryx fossil cast, on display at the Museum.

05/22/2026

The Geology Museum will be closed on Monday, May 25, in observance of Memorial Day. Regular hours will return for the rest of the week.

05/20/2026

Spring is a time of snowmelt, fresh flowers, and warm breezes for the first time in months! To celebrate this season of new beginnings, the Geology Museum is highlighting some Spring Starters; specimens that evoke new beginnings over Earth’s history.

Our second Spring Starter is one you might have heard of before. Archeopteryx originally gained fame when it was found just a few years after Charles Darwin published On the Origin of Species. It is heralded as an example of a transition fossil, exhibiting traits of dinosaurs and birds. With new technologies for examining fossils, scientists are continuing to learn about these creatures and their place in the evolutionary tree of life. For example, scientists at Chicago’s Field Museum Archeopteryx have used CT scans and UV light on their Archaeopteryx specimens to reveal soft tissue details, including scales on the bottom of the creature's toes and bumps on the roof of its mouth. Their research into the fossil’s feathers leads them to claim that Archeopteryx could indeed fly, but likely in short bursts, similar to a chicken.

Despite being known for over 160 years, new techniques keep shedding new light on old fossils. Swing by the museum and take a peek at this flying pioneer!

📷 Photo: Archaeopteryx fossil cast after the Berlin Specimen, Solnhofen Limestone, Germany. On display.

05/15/2026

Today we are congratulating tour guide and tour coordinator Katie! Originally from Valders, WI, Katie just graduated with her Masters in Water Resources Management. Katie has been with the museum for five years (!!) and loves hearing the kids on tours say silly things and gasp when they learn something new and exciting. With her love of all things water-related, it should not come as a surprise that her favorite specimen in the museum is the Niobrara shark.

Katie is kicking off the summer teaching Bio 102 and looking for a job (with healthcare!). She’s also celebrating her cat, Horchata, earning her “Meowsters” degree. 😺🎓

05/07/2026

Hot off the presses! Specimens from our collection are part of this newly published study which names a new myriapod, Waukartus muscularis, and describes its anatomy in incredible detail. The link to the scientific paper is in the comments if you want to dive in.

A long-neglected fossil seems to show the evolutionary leap that let the ancestors of today’s many-legged arthropods crawl forth from the seas.

05/06/2026

Today we’re celebrating Geology Museum tour guide, Molly! Originally from Milwaukee, Molly is graduating with a Geology degree from UW-Madison this month. She has been a tour guide for the past 2.5 years and she loves interacting with the students on tours, especially when they have goofy things to say. Molly finds it hard to choose a favorite specimen but has narrowed it down to the Platecarpus skeleton or the blacklight display.

Beyond geology, she’s also got a brain for geography and can name every country and capital! Next up she’s heading east to get her Master’s at Boston College studying coastal geography. We wish you all the best, Molly!