13-05-2025
Where rock hunters can find agate stones in Michigan
Known for their integrated colors and patterns, collectors are often amazed at agates that wind up on Upper Peninsula lakeshores.
Known for its diversity and beauty, an agate stone is a form of quartz. It can be translucent and in some cases completely transparent.
Rockhounding, a cooler name for rock collecting, is a favorite pastime for visitors and residents who live in northern Michigan.
Here's what to know about the agate gemstone and where you can find it in Michigan:
Agates are formed when gas bubbles in lava leave a hole in the "vesicle" in the rock, according to the Michigan Department of Environment, Great Lakes, and Energy.
Silica (silicon dioxide) solutions flow into the hole in the host rock and fill it up over time, making the bands, the news release says.
Different chemicals in the solution cause the bands to be different colors.
"Agates are sometimes hard to identify, even for the experts," Mary Ann St. Antoine, a senior environmental quality analyst in the Marquette District Office of EGLE, said in a news release.
Antoine, who said she found her favorite agate in Grand Marais, encourages collectors not to get discouraged when the outside of the rock has a dull, waxy luster.
Agates are often translucent, so collectors should hold them up to the light to see if they transmit some light.
EGLE says the best time for Michiganders to look for agates is after a storm, when the waves have washed up new rocks.
The stones can be found across multiple locations in Michigan including:
Whitefish Point
Muskallonge State Park
Grand Marais Beach
Bay Furnace Beach
Pebble Beach
Agate Beach
Misery Bay
Black River Harbor Beach
Eagle River Beach
These identification techniques, according to the EGLE, can help rock hunters determine the type of rocks they have:
Color(also color of a "streak" if it can be made by swiping the specimen on a piece of porcelain, creating a powder)
Luster (shiny, dull, glassy)
Fluorescence (shines under UV light)
Shape/structure (crystal form or amorphous?)
Breakage (how does it break apart, cleavage or fracture?)
Density/specific gravity (can get an idea by "hefting" to see if it's heavy for its size)
Magnetism
Smell
Radioactivity
Yooperlite is a fluorescent rock that glows in the dark under ultraviolet light. It became known when a U.P. resident discovered them in 2017, according to a news release.
According to the EGLE, one person can not exceed 25 lbs total per year on state-owned and public trust lands.
This article originally appeared on Detroit Free Press: What to know about agates, rock collecting in Michigan
