4.1" Midcontinent Rift Section with Fluorite - Ontario, Canada

Midcontinent Rift Section with Fluorite - Ontario, Canada #281073

This is an interesting 4.1" wide piece of the Midcontinent Rift. The fracturing of the the Precambrian-aged Rove Formation caused by this rift can be seen in detail in this specimen. The fragmented rock was later filled in with quartz, amethyst, and/or smoky quartz, creating this unique breccia.

The crystal filled pockets of this specimen feature green fluorite which fluoresces a vibrant purple-blue under shortwave ultraviolet light. Accumulations of pyrite can also be seen within the hot rock.

Comes with an acrylic display stand.

The Midcontinent Rift was a major geologic event that occurred approximately 1.1 billion years ago in what is now the Lake Superior region. During this time the Midcontinent Rift System, also known as the Keweenawan Rift, was splitting east and west North America apart from each other. The rift spanned from Oklahoma/Kansas up through Iowa and Minnesota, arching over into Ontario and back down through Michigan, possibly into Ohio. It's believed that compressive forces from the Grenville Orogeny played a role in the rift's failure, leaving behind faults and zones of fracturing in the host rock, along with deposited gabbro, basalt, and granite intrusive rocks.

During the Pleistocene Epoch, glaciers carved out the rift valleys which were later filled in with water, resulting in Lake Superior's existence and unique shape.

View All Mineral Specimens