From the shores of Lake Erie in the north to the winding Ohio River in the south, and from the Indiana border in the west to the Appalachian foothills in the east, Ohio’s diverse landscape holds hidden treasures.

While not typically known for opals, the Buckeye State has some surprising spots for gem enthusiasts. Today, we’ll reveal the top three locations to find opals in Ohio.

We’ve done the research to save you time and effort. No need to scour the entire state – we’ll guide you straight to the most promising sites.

How Opal Forms Here

Opal forms here through a fascinating natural process. When water containing silica seeps into cracks and voids in rocks, it begins to evaporate, leaving behind tiny silica spheres.

Over time, these spheres stack in a grid-like pattern, creating opal. This process can take millions of years!

The colors in opal come from the way light refracts through the silica spheres. Different conditions in the ground, like the type of rock and the presence of other minerals, can affect the opal’s type, color, and quality.

The Types Of Opal

There are several incredible types of Opal that can be found in the US as well as in our state. Each is uniquely beautiful and interesting including:

Common Opal

Common opal, also known as “potch,” stands out from other types of opal due to its lack of play-of-color, the iridescent display seen in precious opal. Instead, common opal features consistent, solid colors like white, pink, yellow, green, and blue.

It typically has a waxy to pearly luster and ranges from opaque to translucent. To identify common opal, look for its uniform color and absence of the shimmering color flashes found in precious opal.

Common opal forms under similar geological conditions as other opals, where silica-rich water seeps into rock cavities and slowly hardens over time. This process usually occurs in areas with volcanic activity or hot springs, where silica deposits are prevalent.

Fire Opal

Fire opal is known for its warm, vibrant colors, ranging from yellow and orange to deep red. Unlike precious opal, fire opal may or may not display the play-of-color, but its fiery body color makes it unique.

To identify fire opal, look for its bright, translucent to transparent appearance and the absence or presence of play-of-color within the warm hues.

Fire opal forms in volcanic regions where water rich in silica interacts with hot lava, filling cavities and fractures within the rock. Over time, the silica solution hardens, creating opal.

Visually, fire opal’s appeal lies in its vivid, flame-like colors that can be either uniform or exhibit internal flashes of color.

Boulder Opal

Boulder opal forms within the ironstone boulders of its host rock. Unlike other opals, boulder opal features precious opal veins intertwined with the natural rock, creating a beautiful contrast.

This opal is distinguished by its combination of colorful opal patches and the surrounding matrix, which can include ironstone or sandstone. To identify boulder opal, look for its vibrant play-of-color within the darker host rock, often showcasing brilliant blues, greens, and reds.

Boulder opal forms in sedimentary environments where silica-rich water infiltrates cracks and voids within ironstone or sandstone boulders. Over time, the silica hardens into opal, often creating thin seams or patches within the rock.

Hyalite Opal

Hyalite opal, also known as water opal, is a transparent to translucent type of opal that is distinctive for its glass-like appearance and lack of play-of-color. Unlike precious opal, which displays a rainbow-like iridescence.

You can identify hyalite opal by its clear to milky appearance, often with a slight green or blue fluorescence under UV light.

Hyalite opal forms in low-temperature hydrothermal environments, typically in volcanic regions. It precipitates from silica-rich fluids that fill cracks and voids in the host rock. This process can occur relatively quickly compared to other opal types.

Visually, hyalite opal resembles droplets of water or glass, often appearing as smooth, botryoidal (grape-like) formations. Its transparent nature makes it unique among opals, and its slight fluorescence adds to its allure.

Black Opal

Black opal is a rare and highly prized variety known for its dark body tone, which enhances the vibrant play-of-color. Unlike other opals, black opal has a deep background color, ranging from dark gray to jet black, making the iridescent colors more striking.

To identify black opal, look for its intense, dark base color coupled with brilliant flashes of blues, greens, reds, and other hues.

The presence of iron and carbon contributes to its dark body color. In the United States, black opal is primarily found in the Virgin Valley of Nevada, known for its rich opal deposits.

Crystal Opal

Crystal opal is known for its transparent to translucent body, which allows the play-of-color to shine through brilliantly. Unlike common opal, which is opaque, crystal opal’s clear or semi-clear nature enhances its vibrant internal colors.

To identify crystal opal, look for its see-through quality combined with flashes of color that can include blues, greens, reds, and more.

Its unique transparency sets crystal opal apart, making it a favorite among gem enthusiasts and collectors for its ethereal beauty.

Wood Opal (Opalized Wood)

Opalized wood is a fascinating form of petrified wood where the organic material has been replaced by opal. Unlike other opals, opalized wood retains the original structure and texture of the wood, creating a unique blend of organic and mineral elements.

To identify opalized wood, look for its wood grain patterns and opalescent sheen, often displaying a range of colors from white and brown to vibrant reds and greens.

Opalized wood forms under specific conditions where wood is buried in silica-rich sediment. Over millions of years, the silica solution gradually replaces the organic wood material with opal, preserving the wood’s original structure in stunning detail.

Contra Luz Opal

Contra Luz opal reveals its vibrant play-of-color when illuminated from behind. Unlike other opals, which display their colors through surface reflection, contra luz opal’s brilliance comes to life with transmitted light.

To identify contra luz opal, hold the gem against a light source and observe the internal flashes of color, which can include vivid reds, blues, greens, and purples.

This opal forms in volcanic environments where silica-rich water infiltrates cracks and cavities in the host rock. As the water evaporates, it leaves behind silica deposits that eventually solidify into opal.

Visually, contra luz opal appears nearly clear or milky when viewed without backlighting. However, when backlit, it displays stunning, colorful patterns that seem to glow from within.

What Rough Opal Looks Like

When you’re out looking for rough opal on your own it’s important to know what you’re looking for. This is what you need to look out for:

Look for exteriors like this

Look for play-of-color

Opal can display a range of colors, but what sets precious opal apart is its play-of-color—vivid flashes of multiple colors that change with the angle of light. Even in rough form, you might see hints of these colors peeking through.

Common opal lacks this feature and typically appears as a solid color like white, blue, or pink.

Check for a glassy or waxy luster

Opal often has a distinctive glassy or waxy luster. When you find a potential opal, examine its surface.

It should look shiny and smooth, almost like glass, even if it is still encased in a matrix or rough exterior.

Assess the density and weight

Opal is generally lighter than rocks of a similar size. When you pick up a piece of rough opal, it should feel lighter than expected.

Additionally, opal is relatively soft, with a Mohs hardness of 5.5 to 6.5, so it can be scratched more easily than quartz or other harder minerals.

A Quick Request About Collecting

Tips on where to look

Once you get to the places we have listed below there are some things you should keep in mind when you’re searching:

Search in Sedimentary Rock Formations

Opal can also form in sedimentary rock formations where silica deposits have accumulated over time.

Focus on areas with ancient lake beds or clay deposits, as these environments are conducive to opal formation.

Check Dry Creek Beds and Gullies

Dry creek beds and gullies can be excellent places to find opal, as water flow can erode and expose opal-bearing rocks.

Look for exposed rock and gravel in these areas, especially after rainfall or seasonal flooding.

Investigate Old Mining Sites

Abandoned or historical mining sites can be rich in opal and other minerals. These areas often have tailings and discarded rock that may still contain opal.

Always seek permission if the land is privately owned and follow safety guidelines.

Look for Indicator Minerals

Certain minerals can indicate the presence of opal. Look for rocks and soil containing ironstone, sandstone, or clay, as these materials often coexist with opal deposits.

Additionally, finding quartz or chalcedony can suggest nearby opal.

Some Great Places To Start

If you’re eager to hunt for opal in Ohio, there are several prime locations throughout the state that are particularly promising for enthusiasts. Exploring these sites can enhance your chances of discovering beautiful opal specimens:

Marble Cliff Quarry

Located just northwest of Columbus, Marble Cliff Quarry in Franklin County is a fascinating site for gemstone enthusiasts. This former quarry is known for its unique geological features, providing a diverse landscape for rockhounding.

The area is characterized by rugged terrain, with exposed rock faces and scattered gravel deposits that can be explored.

While Marble Cliff is not widely recognized for opal, the potential for discovering this beautiful gemstone exists among the various materials found in the quarry.

Visitors can search along the edges of the lakes and in the gravel beds, where water erosion may have revealed hidden treasures.

Flint Ridge

Flint Ridge is located in the central part of Ohio, nestled between Newark and Zanesville. This area is renowned for its rich geological history, featuring an eight-mile-long vein of high-quality flint.

Flint Ridge is not only significant for its flint but also for the presence of precious opal, which has been discovered in quarry pits and ancient workshop sites scattered across the ridge.

These sites, remnants of Native American quarrying activities, offer a unique glimpse into the past. The landscape is characterized by rolling hills and numerous ancient quarries, making it an ideal spot for gemstone enthusiasts.

Visitors can explore the trails that lead to these historic sites, where opal can often be found among the gravels and remnants of flint extraction.

Bill Moose Run

Nestled in the heart of Ohio’s capital city, Bill Moose Run is a hidden gem for opal enthusiasts. This meandering stream, situated in the north-central part of Columbus, cuts through the Devonian-era Ohio Shale.

The stream bed is dotted with shale concretions, some of which may contain opal. While opal is a rare find in Ohio, Bill Moose Run’s unique geology makes it a promising spot for the adventurous rockhound.

Scan the cobble-filled areas and sandy islands for any signs of the iridescent gemstone. With permission from local authorities, you can explore this urban stream and potentially uncover your own piece of Ohio’s geological history.