Fonda Locality Herkimer Beds

Fonda Locality Herkimer Beds

Upstate New York Herkimer Diamond formations vary significantly from one

location to another.


Though all are technically metamorphic sedimentary (meaning altered or changed

sediment deposits), each has its own characteristics or 'signature'.

The Fonda location boasts what may be some of the largest of these spectacular

doubly-terminated crystals.

 Herkimer Diamond Single 2        

The overall structure of the formation at this location is that of a rippled or

dune-like layered (stratified) limestone bed, with an abundance of vugs, or

pockets, where the crystals have formed, often times completely undisturbed.

What follows is a general description of the Herkimer beds at Fonda where our

claim lies.


Topsoil at the original forest floor - 8 to 24 inches. Many quality crystals can

be collected in the topsoil.


Stromatolites layer - 8 to 16 inches. This stratum resembles a patio constructed

with large blocks, having a space of around an inch between the blocks. The

blocks themselves are very hard, yet porous and rife with mini-pockets up to

about the size of a golf ball. Many high-quality crystals can be found in the

blocks, and in the spaces between.


Shatter rock - 8 to 18 inches. Crumbly in places, can be swept up with an iron

rake. Other sections are quite solid though easily broken up. Sometimes a few

halfway decent specimens show up in the shatter rock, most were formed with

interruptions and imperfections.


In these photos, you can actually see the different layers.  These photos are quite old - the claim's footprint is much different now.  Most of what you see here is gone.    

Mining claim Fonda NY

Caprock - 6 to 14 inches. Fairly hard, mostly barren limestone layer. Riddled

with cracks and moves fairly easily.


Pocket layer or 'goonie layer'. This is where the big ones come from. Ranges

from 16 to 32 inches, most of the crystals are found in the bottom one-third of

the stratum. While this layer has many cracks, it varies from quite soft to

extremely hard material.



Hard rock layer. From 4 to 6 inches thick, a challenge due to the absence of

cracks and the extreme hardness of the rock itself. Barren or nearly so. Some

crystals formed here but are mostly bound to the host and shatter during



Second hard rock layer immediately below that one, this layer even thicker at 6

to 10 inches, likewise almost crack-free and extremely difficult to move. This

is the most daunting layer in the claim.


Drusy layer (yay)!  This is the 'fun' stratum. Excellent specimens of drusy

encrusted limestone with water- clear Herkimer points perched on top. Sadly the

layer is no more than 7 inches thick. Thankfully it lifts easily and gives up

its treasures readily.

 Herkimer Diamond Drusy 11

Second cap rock layer below this, 4 to 6 inches deep. Primarily worthless, not

especially difficult to remove.


Second drusy layer - this stratum is rarely reached by any miner, for the simple

reason that it lies some 12 to 14 feet below the surface. I'm told there's

either drusy in it - or not. And if it's there sometimes it's good. And

sometimes not. We are scratching the surface of this layer after eight seasons

of dedicated excavation.

The claim currently has sections representing each stage.  We will surely never get bored! 



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1 comment

This is the best explanation I have seen about layers and the practicalities of mining…….i could picture each clearly and hear the hammer ringing in my ears with the distinct sounds each layer would make. Thank you!

Dawn Holcombe

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