14 Gems & Rocks Found in Michigan

Michigan is a gem for rockhounds and gemstone enthusiasts, showcasing a diverse array of minerals, fossils, and rare stones. From the iconic Petoskey stones along Lake Michigan to the elusive Chlorastrolite (Greenstone) on Isle Royale, the state is rich in geological wonders.

Explore Michigan’s unique treasures, including the UV-glowing Yooperlite, the vibrant Leland Blue Stone, and ancient glacial Pudding Stones. We’ll also delve into classic minerals like Jaspilite and Thomsonite, offering tips on the best collecting locations across the state. 

Gems & Rocks Found in Michigan including Petoskey stones, chlorastrolite, Lake Superior agates, jaspilite, Yooperlite, pudding stones, Fordite

 

Here are 14 notable gems and rocks that can be found in the state:

Petoskey Stones

Petoskey stones are the fossilized remains of coral, specifically Hexagonaria percarinata, from the Devonian period around 350 million years ago. These ancient corals have been turned into stone through a process where calcite or dolomite replaces the original coral structure, preserving the distinctive hexagonal patterns that make Petoskey stones so recognizable. When wet or polished, these patterns exhibit a striking starburst effect, bringing to life the stone's ancient origin.

Petoskey stones, fossilized coral from Michigan

Petoskey stones, with their light hues of gray, beige, or tan, are not only durable but also transform when wet or polished, revealing their intricate hexagonal patterns more distinctly. These stones, hard enough to withstand being crafted into jewelry or decorative items, carry with them an aura of good luck or prosperity, cherished by those who find them.

Petoskey stones are most commonly found along the shores of Lake Michigan, particularly near the city of Petoskey, as well as in the surrounding areas of Charlevoix and Traverse City. The best time to search for them is in the spring when wave action uncovers new stones along the shoreline.

As the official state stone of Michigan, Petoskey stones reflect the state’s ancient marine history and its rich fossil record. They are a popular choice for jewelry and decorative items, admired not only for their aesthetic appeal but also for their cultural significance. Beachcombers and collectors actively seek them out along the shores, where they are regarded as a piece of Michigan's natural history and a symbol of its geological heritage.

Chlorastrolite (Greenstone)

Greenstone, also called Chlorastrolite or the Michigan Greenstone, is a rare variety of the mineral pumpellyite. It is characterized by its distinct green color and turtle shell-like pattern, making it a prized semi-precious gemstone.

Chlorastrolite, greenstone specimens from Isle Royale National Park, Michigan

Chlorastrolite are usually small, ranging in size from a few millimeters to an inch, and are characterized by a dark green color with a distinctive radiating or stellate pattern that resembles a turtle's shell. This pattern forms due to the crystal's radial growth from a central point. Greenstones are typically found as small, rounded pebbles or embedded within amygdaloidal basalt, a type of volcanic rock characterized by gas vesicles.

Greenstones are primarily found on Isle Royale and in the Keweenaw Peninsula in Michigan's Upper Peninsula. While Isle Royale is a protected national park where rock collecting is prohibited, the Keweenaw Peninsula remains a popular location for finding these stones.

Chlorastrolite was designated Michigan’s official state gemstone in 1972, reflecting its cultural and geological significance to the state. It is highly sought after by collectors and jewelers, often polished into cabochons for rings, pendants, and earrings.

Lake Superior Agate

Lake Superior agates are banded, semi-precious gemstones formed from layers of microcrystalline quartz (chalcedony). These agates are known for their red, orange, and brown banding, caused by iron oxidation.

Agate (Lake Superior Agate) found on the floor of Lake Superior, offshore Keweenaw Peninsula, Michigan

The most distinguishing feature of Lake Superior agates is their banding patterns, which can be concentric, fortification-like, or even parallel. The colors often range from deep red and orange to shades of white and gray. They are durable and can be polished to a high sheen, enhancing their natural patterns.

Lake Superior agates can be found along the shores of Lake Superior, especially on the Keweenaw Peninsula and in the Upper Peninsula. Beaches, gravel pits, and other areas where glacial deposits are common are ideal hunting grounds for these agates.

They are significant not only for their aesthetic qualities but also for their geological importance, as they are believed to have formed from volcanic activity and subsequent sedimentation millions of years ago. The agate's popularity in jewelry and crafts has made it a cherished collectible, symbolizing the natural beauty of Michigan's landscape.

Jaspilite

Jaspiliteis a banded iron formation composed of alternating layers of chert, jasper and iron-rich minerals, such as hematite or magnetite. It formed billions of years ago as layers of sediment accumulated in ancient seas, eventually becoming compacted and metamorphosed into its current state.

Lake Superior Jaspilite with vibrant red, black and silver bands

This rock is primarily formed in ancient marine environments where the deposition of iron and silica occurred over millions of years.

Jaspilite is a captivating gemstone known for its striking bands of red, black, and gray. These vibrant colors are the result of iron-stained chert and iron oxide minerals. The bands can vary from smooth to wavy, creating unique and visually appealing patterns. With its hardness and density, jaspilite is ideal for polishing and crafting into stunning jewelry or decorative objects.

Jaspilite is found in the Iron Ranges of Michigan, particularly in the Marquette Iron Range near Negaunee. These formations are significant because they are associated with some of the earliest forms of life, where the iron oxide bands are believed to have been influenced by the oxygen production of ancient cyanobacteria. Economically, jaspilite indicates areas where iron ore might be mined, although the rock itself is more often sought after for its ornamental value or by collectors interested in geological history.

Yooperlite (Glowing Rocks)

Yooperlite is a type of syenite rock that contains a lot of fluorescent sodalite. This gives it a bright orange or yellow glow when you shine ultraviolet (UV) light on it. The name "Yooperlite" comes from "Yooper," a colloquial term for residents of Michigan's Upper Peninsula, reflecting the rock's origin and the local pride in its discovery.

Yooperlites glowing under UV light from Lake Superior beach in Michigan

Under normal light, Yooperlite rocks appear as gray or speckled stones, but when exposed to UV light, they reveal a vibrant glow due to the presence of fluorescent sodalite. This property makes them a unique and popular find among rockhounds and collectors. Yooperlite is relatively durable and can be polished for decorative purposes.

Yooperlite is primarily found along the shores of Lake Superior, especially in Michigan's Upper Peninsula. The beaches near the Keweenaw Peninsula, Whitefish Point, and other coastal areas are popular places to hunt for these fluorescent rocks.

Yooperlite has become a popular attraction for rockhounds and tourists who enjoy nighttime "Yooperlite hunting" with UV lights. The discovery of these rocks has added a new layer of interest to the state's mineral hunting traditions.

Pudding Stones

Pudding Stones are conglomerate rocks that consist of a mixture of rounded pebbles—often jasper, quartz, and chert—embedded within a finer-grained matrix. These stones are notable for their multicolored appearance, with the matrix often being white or grey, while the pebbles appear in various colors such as red, brown, or black.

Michigan Pudding Stone showing pebbles embedded in jasper matrix

 

The texture of pudding stones is rough and coarse due to the embedded pebbles, although they can be smoothed and polished for decorative use. Their formation is attributed to glacial activity, which carried and deposited the stones from Canada into Michigan during the Ice Age.

Pudding stones are most commonly found in the Lower Peninsula, particularly in the northern part, near areas like Drummond Island and around Lake Huron. They can also be found along the shores of rivers and lakes throughout the state. Their significance lies in their beauty and the geological story they tell of ancient riverbeds and glacial movement, making them popular among collectors and educators.

Fossiliferous Limestone (Fossil Soup)

Fossil soup, a colloquial term for fossiliferous limestone, is a type of sedimentary rock composed of limestone that contains a high concentration of fossil fragments. These fossils can include shells, coral, crinoids, brachiopods, and other marine life from ancient sea beds, giving the rock a "soup-like" appearance due to the mixed fossil content.

Tumbled Michigan 'fossil soup' fossiliferous limestone slabs with a variety of fossils embedded

Fossiliferous limestone typically appears gray or beige, with numerous fossil inclusions visible throughout the rock. The fossils vary in size and shape, creating a textured surface. When polished, the fossils stand out, making the stone more visually appealing and emphasizing its ancient origins.

In Michigan, fossiliferous limestone is prevalent across the state, with key locations in Alpena and Rogers City. The Rockport State Recreation Area near Rogers City is especially noteworthy, where visitors have the opportunity to explore old quarry remnants in search of fossils. Other fruitful areas for discovering this rock type include various quarries, beaches, and outcrops, particularly around the Great Lakes.

The significance of fossil soup lies in its ability to preserve a snapshot of prehistoric life, allowing scientists and enthusiasts alike to study and understand the evolution of marine ecosystems. Fossiliferous limestone is also important for educational purposes, as it serves as an excellent resource for geology and paleontology courses.

Septarian Nodules (Lightning Stones)

Septarian nodules, locally known as lightning stones, are concretions formed from sedimentary materials, often consisting of calcite, aragonite, and limestone. The name "septarian" comes from the Latin word "septum," meaning a partition, as the stones feature internal cracks and separations filled with minerals.

Lightning Septarian Stones from Michigan Great Lakes

Septarian nodules are round to oval-shaped stones with a distinctive pattern of cracks (septa) running through them, creating a network-like appearance. These cracks often contain yellow or brown calcite, contrasting with the gray limestone or darker matrix. They are called "Lightning Stones" because their cracked patterns resemble lightning bolts. Septarian nodules in Michigan include the shores of Lake Michigan, particularly around the Alpena area.

Septarian nodules are prized by collectors for their unique internal patterns. They are often cut and polished to highlight the intricate designs formed by the mineral infills. Culturally, they're believed to enhance communication skills and are said to be stones of grounding and connection with the Earth's energies, reflecting the processes of nature through their formation and healing cracks.

Unakite

Unakite is a metamorphic rock that is altered granite composed primarily of pink orthoclase feldspar, green epidote, and colorless to gray quartz. Unakite is easily recognizable by its mottled green and pink appearance, which results from the combination of epidote (green) and feldspar (pink). 

Unakite stones from Lake Superior, Michigan

Unakite is known for its visually appealing appearance, often displaying intricate patterns and textures. It is a relativelyhard stone, making it suitable for various applications. It's named after the Unaka Range in North Carolina, but it's also found in Michigan, particularly in the Keweenaw Peninsula and along the shores of Lake Superior where glacial action has scattered it.

Unakite is often used as a decorative stone in jewelry and carvings. It is also associated with metaphysical properties, believed by some to promote emotional healing and balance. Its attractive appearance and unique color patterns make it a favorite among gemstone collectors and hobbyists.

Thomsonite

Thomsonite is a zeolite mineral, characterized by its radial aggregates or fine needle-like crystals, often found in basalt vesicles or amygdaloidal cavities. It exhibits colors ranging from white to pink, green, or yellow, and is noted for its pearly luster.

Thomsonite stones found on a beach near Lake Superior, Michigan

Thomsonite typically displays concentric bands or eye-like patterns, with colors ranging from white, pink, green, to brown. Its surface often has a pearly or vitreous luster, and some specimens display chatoyancy, giving the stone a shimmering effect. Its surface may show a pearly luster, and some specimens are even chatoyant, meaning they exhibit a shimmering effect.

Thomsonite is mainly found in the Keweenaw Peninsula, especially around the shores of Lake Superior near Grand Marais. Thomsonite is highly valued by collectors for its rarity and eye-catching patterns. It is frequently used in jewelry, especially as cabochons, due to its visual appeal.

Datolite

Datolite is a borosilicate mineral that forms in hydrothermal veins, often associated with copper deposits. In Michigan, datolite is frequently found with native copper, which imparts unique colors to the mineral, especially in the copper-rich regions of the Upper Peninsula.

Datolite from Keweenaw Peninsula, Michigan

Datolite often appears in light shades of pink, white, or green and occasionally in yellow or blue hues. Its waxy or glassy luster makes it visually appealing, and it can form in botryoidal (grape-like) shapes or as small, angular crystals. Polished datolite reveals beautiful patterns, sometimes with speckles of copper inclusions from the surrounding rock.

Datolite is found mainly in the Keweenaw Peninsula, particularly in areas such as the Quincy Mine and the Mohawk Mine. These historic copper mining sites have yielded some of the finest specimens of Datolite, making them a popular destination for rockhounds. The significance of Datolite in this region comes from its association with the copper mining history, where it's found in the veins or as nodules in the host rock. Collectors value Datolite for its color diversity and the challenge in extracting it due to its hardness and the complexity of the locations where it's found.

Native Copper Nugget

Native Copper Nuggets are naturally occurring pieces of copper, characterized by their metallic luster and malleability. Unlike processed copper, these nuggets can be found in their elemental form, often exhibiting unique shapes and sizes. They can range in color from reddish-brown to a metallic silver, and their surfaces may be shiny or oxidized, displaying various patinas. Native copper is primarily composed of pure copper, making it an attractive option for collectors and artisans alike.

Copper Nuggets from Michigan

Michigan's Keweenaw Peninsula is famous for its native copper deposits. Areas around old copper mines, such as those in Calumet, Houghton, and Copper Harbor, are popular sites for finding native copper nuggets. Some can also be found along Lake Superior's shoreline, where natural erosion and historic mining activity have exposed copper pieces. 

Native copper holds significant historical, cultural, and economic importance in Michigan. It was extensively mined by indigenous peoples for thousands of years before modern mining began in the 19th century, and the region’s copper deposits played a crucial role in the development of Michigan's mining industry.

Leland Blue Stone

Leland BlueStone is not a natural gemstone but rather a type of slag, a byproduct of the iron smelting process that took place in the 19th century in Leland, Michigan. The stone is essentially a glassy material formed from the leftover impurities that were discarded into Lake Michigan during the iron ore smelting process. Over time, these slag deposits have been polished smooth by the lake's waves.

Leland Blue stone from Northern Michigan

 

Leland Blue Stone is known for its varying shades of blue, from light to dark, although it can also appear in greenish, purplish, or grayish hues. It often has a glassy or smooth appearance, with occasional pockmarks, air bubbles, or streaks resulting from the impurities in the slag. These inclusions give each piece a unique character.

Leland Blue Stone is primarily found in the Leland area along the shores of Lake Michigan. The beaches near the Leland Harbor are popular hunting spots for these stones, especially after storms when the waves uncover new pieces.

Although not a naturally occurring gemstone, Leland Blue Stone has become a local favorite in Michigan due to its historical ties to the region's industrial past. It is used in jewelry making and other crafts, often set in rings, pendants, and other decorative items. The stone serves as a reminder of Leland's history and is a popular souvenir for visitors.

Fordite (Detroit Agate)

Fordite, commonly referred to as Detroit Agate, is a unique man-made material that originated from layers of automotive paint overspray accumulating on equipment and floors in car factories, particularly during the mid-20th century. As paint was applied over time, the buildup hardened and was repeatedly baked in ovens used for curing car paint, resulting in striking, multi-layered "stones."

 

Detroit Agate (Fordite) is a man-made gemstone created from hardened automotive paint found exclusively in Detroit, Michigan

The swirling patterns and vibrant bands of Fordite closely resemble the banding of natural agate, which is why it has earned the nickname “Detroit Agate.” Its lightweight nature makes it easy to cut and polish, contributing to its popularity among jewelry makers.

What truly sets Fordite apart are its vivid, colorful bands, featuring layers of red, blue, white, green, black, and metallic hues. These layers formed as various colors of paint were applied, and the baking process created a durable, enamel-like surface. When cut and polished, Fordite reveals intricate patterns reminiscent of natural gemstones, yet with a distinctive automotive-themed color palette.

Collectors and artisans can occasionally find Fordite sourced from old automotive plant sites or from individuals who salvaged this material before the factories were modernized or demolished.

In Conclusion, Whether you’re a seasoned rockhound or just starting out, Michigan offers a variety of gems and minerals to discover. From the fossilized beauty of Petoskey stones to the glow of Yooperlite under UV light, the state is rich in geological treasures. Explore the shores of the Great Lakes, the Keweenaw Peninsula, and old mines to experience the thrill of finding your own piece of Michigan’s natural history.