Thursday, May 28, 2015

5/28/15 Report - Unique Beach Treasures. Fossil Shells With Calcite Crystals

Written by the TreasureGuide for the exclusive use of

Sometimes you can find fossils on the beach that are a million years old.  That hasn't been the case much lately though.  Conditions have been too poor, and like with cobs, some of the best places  have been covered with renourishment sand.

Whelk Shell Fossil Photographed in Black Light.

Did you know that naturally formed gems have  been found on the Treasure Coast beaches?  I'm not talking about those that have been lost at some time.   I'm talking about gems that formed and were never before touched by man.

They aren't diamonds, rubies, or emeralds either.  What I'm talking  are fossils shells filled with crystals.  I'm talking about fossil shells that are thousands or millions of years that have turned into crystal gardens.

You've probably heard of Ruck's Pit.  I'm not talking about those either, but the web site for the Fort Drum Crystal Mine (present name for Ruck's Pit) tells something about how they form.  Here is what it says.

The crystals form inside of the clam shells by a long process. "The calcite is dissolved from the fossil sea shells by acidic groundwater and then transported downward where it then reprecipitates inside the shells of the clams (called quahogs) and occasionally other mollusks," explained Means. Means further explained that the calcite crystals actually form just below the water table in water that is supersaturated with calcite (calcium carbonate).

Talking about Ruck's Pit again, the web site says, The deposit is actually a nearshore marine deposit that represents a former shoreline, " said Harley Means, assistant state geologist, Florida Geological Survey, Florida Department of Environmental Protection. Means explained that sand and fossil seashells found in the mine are thought to be several million years old...

Here is the link to the Fort Drum Crystal Mine Web Site.
You can visit the Fort Drum Crystal Mine to search for fossils for $45 per person until June when the price increases to $60 per person.
Long before global warming the sea was much higher than it is today.  Things come and go.
Back to the beach.   There are deposits of calcified fossil shells found at other places besides Ruck's Pit.  An occasional shell with calcite crystals can be discovered on the beach.  The one shown at the top of this page is one example.

Same Whelk Shell Shown Above
Closeup In Regular Daylight.

In this blog I've shown both fossil shells and bones found on Treasure Coast beaches that contain calcite crystals.  One neat small fossil bone that was found on a Treasure Coast beach has calcite crystals in the hollow of the bone.
Certain minerals fluoresce in ultraviolet light.  That is what you see in the picture at the top of the page.  It isn't easy to photograph objects under black light, but I think you can see some of the rich purple and yellow fluorescence in that photo.

I have also used a black light to find certain fluorescent gem stones such as rubies and garnets.  The black light really makes them pop. sells fossils and shows one calcite crystal fossil conch shell on the site.  I found the following description of that fossil shell instructive.
Here it is.

Okeechobee County, Florida, USA
PLEISTOCENE PERIOD:  1.81 million years - 10,000 years ago
Fossils that have been formed or filled with gem grade minerals are amongst the rarest and most beautiful of all.  The highly uncommon geological occurrence of a well-preserved fossil formed out of stunning gemstone grade minerals is why these specimens are so passionately coveted by both fossil and mineral fanciers, alike.  They make up the rarest of fossils and almost always sell for several thousands if not, tens of thousands of dollars.

In south Florida, there is a gravel shell pit that this strange phenomena can be found - crystals in fossils!  The occurrence of calcite-lined shells is this site's hallmark but the calcite ranges from a light coffee color to a drab burnt honey hue.  Intense yellow gem-grade specimens such as this are not found at the mine but have been found in the same formation of a nearby undisclosed site.  A fossil of this quality, completeness with crystals of this clarity and intensity is no less rare than finding fine grade gemstones of any type from any site in the world - actually rarer since this is a perfect crystal specimen AND a fossil. 
This is a small Busycon species gastropod fossil from the last North American Ice Age Period.  The entire shell's internal cavity has been fossilized with the whorl and inner chamber filled with bright lemon yellow gem-grade calcite crystals.  Nearly the entire shell has been completely replaced with translucent glowing calcite as seen in the above images.  Busycon was a predatory marine whelk that fed mainly on bivalves by attaching itself to its prey with its foot and slowly rasping a hole in the shell of its unfortunate victim.  Whelks can move great distances and can go against tidal currents with the use of its powerful foot.

This specimen was part of an extremely limited find that was made by the quarry geologist NOT at the working mine but at a location nearby that is not part of the commercial operation.  This find was very limited, discovered and collected in the early 1980's and specimens of this nature have never been located since.  This color and quality certainly does not occur at the working quarry.  Of the few rare examples that have hit the market, prices have exceeded $1000.  The color and lack of crystal damage on this beauty easily top those $1000+ examples. This is the only one we will ever offer as it was a rarity unto itself for us to even acquire it.  If you want a stunning and rare mineral AND fossil specimen all wrapped up in one, you could hardly find a more affordable and yet beautiful example.  Guaranteed NO REPAIR and NO RESTORATION.  This beauty is AS FOUND!

The deposit that this prize specimen was collected from offers an abundance of well-preserved fossil marine shells.  Its coquina matrix dates to the Pleistocene and is part of the 'Nashua Formation' being composed of cemented marine fossils with calcite.  

That description is from

Not only have I seen fossil shells with calcite crystals on the beach, I have also seen some in the Indian River.  I don't know how they got there.  They could have been dumped there with road fill for Indian River Drive, but I don't really know.


People say all the time that you can't take it with you when you die, but there is an exception.  The only thing you can take with you is what you give to others.


Happy hunting,