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Introduction to Herkimer Diamond Quartz Crystals

Introduction to Herkimer Diamond Quartz Crystals

by , Intuitively Inspired Designs Find us on Google+
Herkimer Diamond Quartz Crystals: Quartz in general This quartz specifically When, How & Why Where The Crystals Picking & Rating when buying Novice Digging Glossary (the first use of these words is " * " starred*) More Herkimer Facts

Herkimer Diamond Quartz Crystals:

Herkimer Diamond quartz crystals are a uniquely beautiful, natural occurrence* of quartz that are found only only in a small area around Little Falls, NY. There are quartz crystals roughly similar in appearance and occurrence from several other locations around the world they really never match the brightness and clarity of genuine Herkimer Diamonds. I cannot count the number of times I've explained to stunned and disbelieving people that these sparkling crystals are natural, not cut and not polished.

Quartz in general:

Before we talk more about Herkimers or Herkimer-like crystals, let me say something about quartz crystals generally: Unless you count water-ice, quartz is by far the most common mineral on the surface of Earth; yet quartz is so varied it's often unique enough that you can tell exactly where, sometimes within meters or less, on/in the surface of this planet it is from! I'm not going to list any different types of quartz crystals or other types of quartz here, it could never be complete anyway; let it suffice to say most quartz crystals are found in dirt/clay or in volcanic rock and have prisms* that are several to many times longer than wide, often with one termination* and the other end of the prism attached to matrix* or broken from it.
Photos of some other types of quartz, from left to right: Druze* quartz crystals over Chrysocolla, Citrine crystal with Mica, Cross section of amethyst/agate geode, detail of same. Likely all of the above photoed quartzes are volcanic or hydrothermal. The amethyst makes an excellent example of volcanic formation since it is essentially a horizontal cross-section of crystals that precipitated* within a gas bubble that became trapped in lava, first as it cooled quickly the very small crystals that combine to make up the banded agate at the outer edge coated the inside of the bubble followed by the larger amethyst crystals.

This quartz specifically:

Herkimer Diamond quartz crystals are a usually short-prism, doubly-terminated variety* of the Quartz species*: Rock Crystal that precipitated* in water within fossil pockets left in dolomitic limestone (dolomite), a sedimentary rock. The pockets (vugs*) within certain dolomite layers in central NY state they're found in were left by stromatalites, an ancient algae/lichen among the earliest living things on Earth.
I found this wonderful little matrix piece my first day ever mining in Middleville, NY, the Herkimers here are bigger than nickles and have grown around cubic dolomite crystals; the detail on the right is of the upper crystal in the specimen as pictured with a dolomite cube in its bottom right side.

When, How & Why:

As I understand it, the story of the Herkimer's formation is something like this: A very long time ago, 400,000,000 years or so, the portion of the Adirondack mountains of New York where these crystals are found was a Sea, during this time stromatalites grew there. As time passed, this area became covered in sediment that eventually became dolomite; I'm told that where the overburden of dolomite is ten feet thick was originally over a hundred feet of sediment. In water under the ocean is where the Herkimers precipitated, they are aqueous quartz; they grew very slowly, one of the reasons they're so clear.

There are many mineral associations (other minerals found) with herkimers including pyrite and calcite, leaving aside dolomite, anthraxolite is common, usually the vugs are lined with it. Since anthraxolite is a carbon mineral it's possible this is the remnants of the stromatalites.

It is a matter of great speculation at the mine and among enthusiasts why Herkimers are so clear and bright, it's my personal suspicion that it was the anthraxolite acting as a charged-carbon type filter in the fluid that precipitated the crystals. Whatever it is, clearly some action within these crystals makes them remarkably bright, like leaded-glass in some cases. Also a matter of speculation, is whether or not there is any such thing as a true "floater", that is, did any of the crystals precipitate purely out of solution without attachment to anything or do they all have a core? Every miner and enthusiast has their theories, but no one knows these things for sure.


There are other Quartz crystals of similar occurrence, found within stromatalite pockets in dolomite, around the world, but these are easily spotted so something's different. These other crystals are found in Mexico but are very obviously dull (many more enhydrous* crystals though) and often called "Meximers"; and in Patagonia, Argentina, where they're brighter than in Mexico but still you can see the difference. Pakistan too; I'm sure there's occurrences of quartz like this elsewhere in the world too, but it's inappropriate at best and misleading at worst to call crystals from locals other than NY "Herkimer Diamonds".

Herkimer Crystals:

So there is a virtually infinite variety of quartz crystals around, of which Herkimer Diamonds are a type; differentiated by their unique beautiful habit* (shape and appearance) and occurrence (situation in which they're formed and found). Herkimer Diamond crystals are sometimes found in dirt only due to weathering over time, they've all originally come from two types of layers in the dolomite: what at the mine are called "Pockets" and "The Ledge".

"Pockets" are much what they sound like: large vugs found in almost regular spacing along certain layers, random but predictable kind of like trees in a forest. They can range from about the size of a basketball to what a truck tire might occupy or larger. There can be virtually any type of Herkimer crystals within these pockets: big, broken, rust-covered cloudy ones packed in mud, or small perfect crystals and clusters in anthraxolite powder (though this is rare) and anything in between. Any clusters may already be popped apart or still be "naturals". There are also what are called "skeletal" crystals found in the pockets, these are usually larger than a small peach, and seem to be folded into themselves, leaving radial growth lines often trapping water (enhydrous).

"The Ledge" layer is so called because it is below the pocket layer, miners cleared off the pocket layer leaving a ledge. I'm told for a long time diggers disregarded or didn't realize this lower layer was crystal bearing, but now most will agree the ledge is where the finest crystals come from. The vugs within the ledge are usually lined with anthraxolite and are random in spacing and size, but seem to run in layers and it is unusual for them to be bigger than apples; it follows that the single crystals and clusters found in this layer are not as large as many pocket crystals, and in general skeletal crystals are not found in the ledge.

I expect most readers of this guide will be familiar with the most common, 18 or more sided, single crystal habit of the Herkimer Diamond; but I want to add more about the clusters and enhydrous crystals.

Herkimer Diamond crystal clusters are notoriously delicate in their natural form; and it is the rule rather than the exception that when you find a cluster digging it's already popped apart at the contacts between crystals. The best thing to be done in such a case is reconstruct the cluster which is what most diggers do, "natural" (un-popped apart) clusters are rare and treasured. If a digger finds a large pocket of small, popped apart clusters, it is literally a puzzle that can have 10s of thousands of pieces, all the same color and an added dimension, the 3rd, most miners consider the sorting and reconstructing of found crystals to be as fundamental in the process as breaking rock and finding crystal to begin with; so they're not "done" until they've been repaired.

Enhydrous Crystals can be stunning and are a lot of fun. If you're looking at or for crystals with these you want to be sure to get one that is easy to see if that's important to you, some can be difficult but on the other hand some folks just want to know it's there. Also be sure that it's not somewhere in the crystal where it could escape, like next to or attached to a fracture that reaches the surface, especially if it's a freshly dug crystal. I'm told that some enhydrous Herkimers shatter upon being in the Sun's light for the first time, since I've learned this any crystals I've found have been very quickly shaded, just in case, once they've been out of the Earth for a while they're ok. So if you have an enhydrous crystal, be sure to take care of it properly: never leave it in a sunny or hot place like a window sill or a car in the sun since some may dry up (not all will). Worst of all for your enhydrous crystal is letting it freeze, say by leaving it in your car or garden, this can break most any enhydro bearing crystal.

Enhydrous Herkimer with a mote of anthraxolite that moves when turned.

Picking and Rating when buying:

The clearest answer is to pick a crystal that makes you happy, whatever it is about it that does, whether it's its flawlessness or the rainbows refracted from fractures present.

Because natural clusters are so delicate you should expect that any Herkimer Diamond crystal cluster on the market is repaired unless noted otherwise, and if buying Herkimer cluster jewelry you should insist on it: most natural Herkimer contacts will not hold to wear.

Many collectors are interested in rarity, regarding the perfectly flawless Herkimers, I'm fond of saying that one could easily get 10s of thousands of flawless 1 or 2 mm crystals, but that if one had a flawless 2 inch (50 mm) Herkimer they could easily get 10s of thousands of dollars for it: as the crystals get larger not only are they more rare, it also becomes exponentially more rare for them to be flawless. In terms of single crystals, "perfect" 1/4ths-1/2 inch crystals are often found, 1 inch ones are very seldom seen. Single crystals and small clusters like this are highly prized as collectables, healing tools and for jewelry. "Pocket" crystals & clusters and skeletal crystals can be rather large and are collected as specimens and tools.

There is no standard grading or rating system for crystals of this type, so most miners and dealers create their own if they use one. I don't use a rating system at the moment but have one in development.

As in buying any valuable mineral specimen or gemstone, be sure to deal with a scrupulous dealer who represents their offerings honestly and knows and stands behind what they're dealing with, and you're sure to get a crystal you'll be happy with.

Novice Digging:

(coming soon;)
Smokey Herkimer Diamond Crystal
You can see creations of mine featuring Herkimer Diamond quartz crystals in my eBay store, Rainbow Zen Gardens, and elsewhere on the Internets. Thanks for visiting my guide to these lovely, natural beauties, I hope that you've found it helpful, that you're well & are having a lovely day~

Allen, aka intuitivelyinspired


Druze: Descriptive term referring to crystals grown together side by side as in many geodes
Enhydro: a water filled void in a crystal or mineral, sometimes also with gas or other minerals within.
Enhydrous: A crystal or mineral with an enhydro
Habit: The outer and inner form of a crystal, it's faces', edges', and sufaces' characteristics.
Matrix: The host rock or mineral of a particular specimen. A Herkimer on calcite crystals is on calcite matrix; a calcite crystal on a Herkimer is on Herkimer matrix.
Occurrence: The physical situation a mineral specimen is found in, i.e. in clay or stone, refers to layers and associations.
Precipitate: To change from a lighter form of matter to a heavier one, as in from gas to liquid or liquid to solid, to condense, the opposite of evaporate or melt.
Prism: The "Body" of the C-axis of a crystal form, not always but usually the longest axis and faces. In Quartz crystals the (usually 6) non-terminal faces.
Species: A recognized sub-set of a mineral or mineral group with unique characteristics.
Termination: The point or points of completion of a crystal's growth.
Variety: A recognized sub-set of a mineral species with unique characteristics.
Vug: a mineral bearing opening in a rock.

More Herkimer facts: They can be smokey and can have Phantoms. ~There are more than 17 other minerals found with them. ~The Native peoples in the area are known in their own language as "The people of the crystals". ~They seem (to me and most knowledgeable about them when I point it out) to have a cleavage plane that runs parallel between two opposing termination faces (at opposite ends of the crystal). ~There are other quartz crystals found nearby, scepters and "Fonda footballs", that aren't properly called "Herkimer Diamonds". ~Nobody knows for sure when they were first called "Herkimer Diamonds", but they've been called this in "Dana's System of Mineralogy" for over 100 years.