Collecting Calcite Clams in Florida

Florida is a treasure trove for fossil hunters, particularly those seeking calcite fossilized clams. These unique specimens, formed when calcite crystals replace the original clam shells millions of years ago, are prized for their beauty and scientific significance.

Located near Fort Drum in Okeechobee County, Florida, Rucks Pit, also known as the Fort Drum Crystal Mine, has become synonymous with calcite fossilized clams. Once an active limestone quarry from the early 1900s until 2006, this site is renowned for producing extraordinary clams filled with golden-yellow calcite crystals.

The fossils belong to the species Mercenaria permagna and date back to the Pleistocene epoch, approximately 1–2 million years ago. These clams formed when their original shell material dissolved, creating space for calcite crystals to grow in intricate scalenohedral patterns. The resulting specimens often resemble miniature geodes, with translucent crystals that sparkle under light. Some even fluoresce under ultraviolet light, making them highly sought after by collectors.

Florida’s abundance of calcite crystals can be attributed to its underlying marine limestone deposits, which span from the Tertiary period to the present. These formations create opportunities for crystal hunting wherever the limestone is exposed, particularly in active rock quarries. Calcite, the most commonly collected mineral in Florida, often occurs in stunning specimens that combine fossils and crystals.

Calcite Fossilized Clams Collecting in Florida. This is a large Fossil Clam shell on matrix from Florida. Photo: Bryan Major

Visiting Ruck's Pit

Today, Ruck's Pit is a premier destination for those seeking calcite-filled clams. Visitors can pay a fee to dig for these unique treasures on this family-owned property. The site, operated by Eddie Rucks, offers one of the best opportunities to find fossils and minerals in the same specimen. Specimens from this locality date back 1.6 to 2 million years.

What to Expect at Rucks Pit

Loose, gem-quality calcite crystals and crystal clusters. Some individual crystals can be over an inch long. Large, fossilized clams filled with calcite crystal

Other fossilized shellfish, like whelks and olive shells. On rare occasions, you’ll find one of these filled with tiny crystals.

You may also find other fossils, such as sharks' teeth and prehistoric animal bones.

The pit also has a variety of minerals, including quartz, pyrite, and hematite.

Ruck's Pit Calcite Clam. Photo: Rockhounding Florida

Tips for happy hunting

• Visit during the dry season: The dry season (typically between November and April) offers better conditions for digging and uncovering your finds.
• Wear comfortable clothes that you won’t mind getting dirty. Because they will.
• Boots – or other shoes with ankle support – are a good idea. Loose rocks can give you a twist.
• Wear gloves. The tiny, fossilized shells that make up the rock can have rough edges.
• Bring a hammer, chisel, hoe and flathead screwdriver. The driver is a valuable tool for carefully loosening the dirt and rock around your fragile finds.
• Bring newspapers. Calcite is “soft” crystal and easily scratched. Wrap your finds before they go in your bucket.
• Bring a cooler and plenty to drink.
• Wear sunscreen. While there are shade pavilions, when you get the “crystal fever,” you’ll forget how long you’ve been standing in the sun.

When you are digging in the right area, you will find whole beds of clams like these two. Photo: Mineral Movies

Ruck’s Pit is in the midst of a transformation and will eventually become a full-service campground. There’s already a swimming beach at the lake, so if you get too hot, you can take a dip. The lake is also stocked with bass, bluegill, catfish and tilapia for catch-and-release fishing.

Respect the environment: Only collect what you intend to keep and leave no trace behind. Fill in any holes you create and dispose of any waste properly.

Sustainable practices: Limit your collection to avoid depleting the site's resources for future generations of collectors and researchers.

 

Golden calcite crystals inside a fossilized clam shell (Mercenaria permagna) from Rucks Pit, Fort Drum, Florida.

Unearthing these unique geological marvels can be a truly rewarding experience. With proper planning, preparation, and a touch of luck, you might just add a remarkable piece of Florida's natural history to your collection.