Skip to main content

Natural Awakenings Healthy Living Magazine

The Treasure Beneath Our Feet

 by Martin Miron 

Humankind has always been fascinated by gems and crystals, assigning high monetary value to the rarer specimens and even spiritual properties to some. Perhaps we are intuitively attracted to the complex and beautiful matrix that comprises their structure. Northern Michigan provides boundless opportunity for rock hounds of all skill levels to get out in the fresh air, explore, have fun and build their collection.


 Emeralds, one of the “big four” precious gems, along with diamonds, rubies and sapphires, notably have been recorded in an old iron mine in Marquette County. More likely discoveries include semiprecious varieties (think traditional birthstones) and the gamut of garden-variety minerals. Here are just a few of the many possibilities.


Chlorastrolite, Michigan’s state gem, is mainly found along the beaches of the Great Lakes and in Isle Royale National Park. These stones are most commonly pebble-sized and bluish-green in color, with a star pattern of crystals that resembles a turtle shell, commonly called greenstone, a variety of the mineral pumpellyite. Chlorastrolite pebbles often contain other minerals that give them color variations, such as the pinkish hues of thomsonite.


 Agate is a variety of quartz that varies in color, but the defining feature is concentric banding. The prized, striated Lake Superior agate is stained by iron-rich bands that reflect the gemstone’s geologic history. The shoreline from Whitefish Point west to Grand Marais offers some of the best places to find agates. Preferred locations include Lake Superior State Forest Beach, Muskallonge State Park and Whitefish Point Beach.


 Hematite is an iron ore that is black or rusty reddish-black in its raw form, but often a shiny black in its polished gemstone form. They can be found in old mining dumps and along the shores of Lake Superior.

 Jaspilite, also known as banded ironstone, occurs in the knolls between the cities of Negaunee and Ishpeming in the Upper Peninsula, predominantly on a hill called Jasper Hill. Jaspilite specimens, comprising alternating bands of light red jasper and hematite, represent some of the oldest rock formations in existence—formed more than 3,500 million years ago.


 On the Lake Michigan side, Petosky stones, the state’s official state stone (really) is a both a rock and a fossil, often pebble-shaped, that is composed of a fossilized rugose coral, Hexagonaria percarinata. These stones were formed as a result of glaciation, when sheets of ice-plucked stones from the bedrock, grinding off their rough edges and depositing them along the peninsula. When dry, it resembles ordinary limestone, but when wet or polished using lapidary techniques, the distinctive mottled pattern of the six-sided coral fossils emerges, and is sometimes made into decorative objects.


Oddball Yooperlites are normal-looking, gray rocks rich with fluorescent sodalite, that glow a vibrant orange and yellow under ultraviolet light. They are most predominant in the Upper Peninsula along Lake Superior such as on the beaches near the Grand Marais, and the Keweenaw Peninsula. Finding them has become quite a trending hobby. For specifics, visit Tinyurl.com/YooperlitesOrBust.

 For a complete list of minerals found in Michigan, visit Tinyurl.com/MichiganMineralList.

 Exhibits to Visit

 For those that would rather leave the field work to professionals, several institutions offer excellent mineral exhibits and tours.

 -       A.E. Seaman Mineral Museum of Michigan Tech, 1404 Sharon Ave., Houghton (Museum.mtu.edu). The official mineral museum of Michigan has the world’s finest display of minerals from the Lake Superior Copper District.

 -       Bruce Dice Mineralogical Museum, 1740 Knollcrest Circle SE, Grand Rapids (Tinyurl.com/BruceDiceMineralMuseum), on the campus of Calvin University.

 -        The Adventure Mining Company, 200 Adventure Ave., Greenland (AdventureMineTours.com), offers a slate of educational tours in a mine that operated from 1850 to 1920, removing more than 11 million pounds of native copper from the ground.