Here are some of the most common rocks of Lake Superior and fossils that really stand out and anyone at any age can get lucky finding.
Rocks of Lake Superior
The information provided in this article by YesDirt.com is for informational purposes and is subject to change. Laws are updated. Accessibility guidelines and restrictions change. Be sure to confirm the land status and collection rules before you travel to an unfamiliar location or collect any material.
Wisconsin, Michigan and Minnesota have long been known as huge regional repositories for geology and fossils.
Like much of Canada to the north, the Superior Lake area was full of vegetation, life, ancient creatures and plenty of geological movement billions of years before.
As a result, visitors and rockhounds alike will easily be rewarded with finds along the Great Lakes shores of the states.
Agate, Agate and More Agate
Known specifically as Lake Superior Agate, this rock type was a result of volcanic activity in the Great Lakes area billions of years earlier in history.
The agate rocks themselves appear with notable coloring, ranging from yellow to red and orange.
They are common and frequently color the shores of Lake Superior with a distinct range of yellow to rust orange.
Much of this difference is due to the iron in the rock and its subsequent oxidation exposed to water and air.
How much iron is within a given rock dictates the coloring and deepness to the reddish coloring.
Many of the agate finds are banded with a variety of shades versus just one color as well.
Known technically as Halysite corals, these leftover fossils come from animals that were originally jelly in form when they were alive.
Often connected to coral reefs, the Halysite polyps fed on plankton in the passing water, and grew into tubes with various sections as they got older.
As Halysite corals grew in population in a given area, their structures would become coral reefs that dotted the water floor.
In most cases, these water creatures lived at least some 425 million years ago and the remainder are what people find today.
Odd in shape and appearance, a Petosky stone is actually a corallite.
These come in six-sided formations, and they represent the leftover fossil skeleton of another sea-life creature from millions of years ago.
Appearance-wise, Petosky Stones stand out right away because of their distinct appearance and even geometric patterns.
Most people looking at a specimen think the shape and pattern represents a sun with rays.
In fact, the name comes from a historical Ottawa leader, Chief Pe-to-se-ga, which in translation means “rising sun.”
Not associated with the mythical ‘Noids from 1980s Domino’s pizza commercials, Crinoids are also fossils with a notable hole in the middle.
Some folks note they look a lot like Cheerios cereal bits.
The remainder comes from a creature that was related to what we know as a starfish today.
The ancient creature was made up of a number of these Crinoid disks, which would have looked like a tube stack rising from the sea bottom to catch food.
The remainders have been found for centuries along the shores of the Great Lakes, and ancient indigenous peoples used them for jewelry beads in necklaces and similar.
Given the fact that such shells were distinct to the Great Lakes area, tribal trade networks moved jewelry samples far and wide which in turn can be sourced back to Lake Superior today.
Leland Blue Charcoal
One of the few minerals that can be found in the Great Lakes that was not naturally deposited, Leland Blue Charcoal is actually a result of production waste being dumped in the waters.
From 1875 to about 1900 the charcoal came about from the heavy production of smelting iron.
To break up and melt iron from iron ore, significant heat is needed.
The process of heating and burning the ore was done with local beech or maple wood, which turned into charcoal at the end of the burning process.
Since no one had a ready use for the burning byproduct, the companies would then turn around and drop the charcoal in the Great Lakes around Northwestern Michigan.
Today, it washes up on the shore, reminding folks of the area’s industrial past.
One of the world’s most common rocks, granite is also very present in the Great Lakes area.
A hot-fused combination of lots of other rock types, granite tends to be a highly-compressed result of volcanic activity at high temperatures, often involving various other rock that has been remelted repeatedly in magma.
Known locally as honeycomb coral, Favosite involves fossilized tubes that clump together and often resemble a bee honeycomb in shape and organization.
The fossil itself is extremely small and resembles a grid covering over the rock solidified over time.
Otherwise known as greenstone, this mineral is also a result of copper mining in the area of the Keweenaw Peninsula.
Found as a byproduct in the mining going on in the area, the stone itself is a gem.
Technically, the formation is pumpellyite, but the mineral is full of miniscule gas bubbles and pockets.
The creation of the rock resulted from lava basalt flows some 1 billion years ago underneath the land crust on the Peninsula.
A very recognizable fresh water shell, the brachiopod has a distinct shape and pattern that reminds a lot of folks of a lamp structure when lit up.
The shells themselves are a result of upper and bottom formations the animal used when alive.
At first glance, this stone looks like someone’s bad art project.
It is actually a natural aggregate made up of jasper, quartzite and other material.
Created as a sediment of rivers and water channels, the aggregate was compressed together over billions of years.
The material was then moved and deposited into the Great Lake area via glaciers and slow but relentless ice pressure.
Warnings to Note for Rockhounds
A couple of words to the wise regarding finding and collecting stones in the Lake Superior area.
Michigan law restricts rock hounding to a total of 25 lbs of rocks, minerals or fossils from state territory per person per year.
Additionally, federal national parks or territories forbid any stones or mineral material from being taken as well.
These warnings should not be ignored or assumed that the related penalties are light in application.
In other national parks, for example, simply picking up an arrowhead can land a person in front of a federal judge and facing a fine of at least $1,000 if not more.
So, if visiting the area for rocks of Lake Superior, make sure to pay close attention to the exact jurisdiction you’re in first and then follow the rules to the letter.
Remember, it doesn’t take many rocks to make up 25 lbs, especially if they are dense.
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