Herkimer Diamonds

Herkimer diamond is a generic name for a double-terminated quartz crystal discovered within exposed outcrops of dolostone in and around Herkimer County, New York and the Mohawk River Valley. Because the first discovery sites were in the village of Middleville and in the city of Little Falls, respectively, the crystal is also known as a Middleville diamond or a Little Falls diamond.[1]

Herkimer diamonds became largely recognized after workmen discovered them in large quantities while cutting into the Mohawk River Valley dolostone in the late 18th century. Geologists discovered exposed dolostone in Herkimer County and began mining there. The popularity of mining for double-terminated quartz in the Herkimer County outcroppings is what led to the name, Herkimer diamonds. Currently, Herkimer diamonds can be found in large quantity in at least Herkimer,Fulton, and Montgomery counties, and double-pointed quartz crystals have also been found in abundance in Tibet and Afghanistan, as well as in other countries.

Many of the New York crystals are known for their extreme clarity, and Wiccan and New Age belief systems often ascribe specific occult properties and a wide variety of mystical powers to them.

These quartz crystals, which geologists theorize formed extremely slowly in small solution cavities or vugs, have 18 facets (6 sides) and two terminations. There are also larger cavities that are several feet in diameter that are called “pockets”. They can be found clear, cloudy, smoky or even containing a variety of rare impurities. Impurities (rare and general) can include clusters, scepters, enhydro (properly called fluid inclusions), phantom, and bridge crystals. A fluid inclusion contains a water pocket (plus methane or oil, and rarely a crystal) within the crystal, a phantom is a crystal which contains an image of itself within, a skeletal crystal contains a series of crystal edge outlines inside the crystal and a hopper crystal has its faces replaced by a step like pattern.

Mohawk Valley Crystals

Double-faceted quartz crystals are unique to the Mohawk Valley. They are so unique that in ancient times the Indians who lived here were called the “people of the place of the crystals.” 

Today Mohawk Valley crystals—a.k.a. Herkimer Diamonds—are major attractions. While outcrops of crystal-bearing dolostone can be found from Middleville to The Noses, diamond mines open to the public are located near Middleville, Little Falls and Saint Johnsville.

Mohawk Valley Crystals vary greatly in size, shape, color, clarity, impurities. . . . and value.

Of course these crystals are not really diamonds, at least not the ultra-hard, crystal clear carbon-based gemstones that have been the source of wealth for eons. However, they are crystal clear silica-based gemstones that are hard enough to scratch glass . . . and are becoming more valuable each year. They are, in fact, the only double-faceted—pointed on both ends—clear quartz crystals that are not man made. Their rarity in nature, unusual forms, beauty, and popularity among mineral and gemstone collectors, jewelry makers and holistic healers, attract more and more miners to the Mohawk Valley each year.

These diamond mines are not “holes in the ground” in the classic sense; they’re stone quarries or “walls” of dolostone where certain layers of this sedimentary rock contain pockets or “vugs”. Many of these vugs contain handfuls, sometimes bucketfuls, of individual gemstones or clusters of crystals that vary greatly in size, shape, color, clarity, impurities . . . and value.

Dolostone contains pockets or “vugs” that sometime contain handfuls of crystals.

Long on History – Short on Appreciation

These transparent quartz crystals have been around for a long time, some 400 million years according to some scientists. (See Chapter 3) Until upheavals, glaciers, floods, repeated freezing and thawing, and other agents of erosion cut into layers of dolostone, they were trapped in solid rock. Of course it didn’t matter because no one was around to appreciate them until some 9,000 years ago when humans moved into the area. And even then there is no evidence that these earliest inhabitants considered the crystals to be of any practical or religious value. However, thousands of years later the Mohawks collected and traded quartz crystals, and placed them in burial sites, indicating their spiritual significance.

For years Mohawk Valley crystals were called Little Falls Diamonds because they were first found in great numbers by workmen cutting into the dolostone in that area in the 1790s to build locks to bypass the “little falls” on the Mohawk River. Greater quantities were found during the construction of locks for the Erie Canal in the 1820s. When it was determined they were not “real diamonds” and of no practical value, canal workmen and most locals didn’t get overly excited when they found crystals that were cut or blown out of the 450-foot high Little Falls Dolostone formation.

Geologists and a few collectors, on the other hand, did get excited. They discovered other exposed areas of dolostone in Herkimer County that also contained pockets of quartz crystals. Among them were outcrops in Fairfield, Salisbury and Middleville. Herkimer County was recognized as the location of “Exceedingly transparent crystals” in an article in the 1850 volume of Popular Mineralogy by Henry Sowerby. As more geologists and collectors recognized the wide area covered by the dolostone formation containing quartz crystals, they referred to them as Herkimer Quartz or Herkimer Diamonds.

Too Busy Surviving to Dig For Diamonds that Weren’t Diamonds

Most people living in the Mohawk Valley in the 1800s were too busy “surviving” to dig for diamonds that were not really diamonds, but locals who found them in streams and quarries did keep them as “lucky stones” or to give to relatives and friends as keepsakes. Even when dolostone formations were exposed in other areas of the valley during the construction of railroads in the mid 1800s, few people took the time to collect or even consider a market for them.

Famous Worldwide Among Geologists and Collectors

There were, however, a growing number of people who had the time, money and interest to appreciate how truly unique these natural wonders were in the big scheme of things. Many of them were well-educated and well-traveled, and realized that these transparent double-faceted quartz crystals, although abundant in the Mohawk Valley, were rare in geological formations around the world. Through geological associations and later, rock, mineral and gemstone collector organizations (and their publications), Herkimer Diamonds and Middleville became famous worldwide.

A. B. Crim of Middleville had spent much of his life collecting Herkimer Quartz. His collection of “four thousand individual specimens included twins, crystal inclusions, smoky crystals, and matrix specimens,” were exhibited at the World’s Columbian Exposition of 1893 in Chicago. Although the location of Mr. Crim’s collection has been lost to history, his exhibit in Chicago made history by putting Middleville on the world map as the place to find the finest quartz crystals.

Despite such worldwide exposure, mining at Middleville was pretty much a hit and miss operation in the early part of the 20th century. Some collectors chipped away at sections of dolostone beside the canal or railroad beds. A few walked tributary streams and the river, locating crystals imbedded in sand and gravel. At least one farmer charged a nominal fee to allow crystal collectors to mine on his property.


Roads Paved With Diamonds

The value placed on Herkimer Diamonds among most locals can best be illustrated by the opening of the Middleville Quarry in the mid 1900s. Dynamite blasted the dolomite formation on the east side of the river north of Middleville. A crusher reduced the crystal-laden rock to pieces small enough to sell to nearby towns for road fill and for contractors to grade driveways. It was common practice for youngsters to wait until after a rainstorm to find and “harvest” diamonds from the newly spread—and washed—fill. The quarry was closed for a number of years and some collectors in-the-know “snuck in” to find diamonds. This quarry has been sold several times over the years, and is now operated by the Hanson Corporation. Today it’s a giant hole in the ground with the highest dolostone wall in the valley. When not in use, locked gates block entrances . . . and the area is posted.


Miners Pay to Pound Rocks All Day Long

There are two “walls” near Middleville where the public can legally mine dolostone for diamonds. Except for the dolostone, diamonds and digging tools used by miners—and the hedgerow between them—these operations are as different as night and day.



The Herkimer Diamond Mine Resort and the Ace of Diamond Mine are located side by side along West Canada Creek near Middleville.



The Herkimer Diamond Mine Resort is a first class, classy even, tourist attraction that in addition to the “wall” includes a mineral & rock museum and gift store, a campground, cabins, swimming pool and a restaurant.

The Ace of Diamond Mine is a rustic—step back in time—operation where bulldozers, cranes, loaders and other heavy equipment run by long-hair, bearded miners help take down the wall and move rock, so hardrock miners and tourists can get to the diamonds. A rough-wood building serves as the mining office, gift shop, repository for mining tools, and a supply store for the campground out back.


More To Finding Diamonds Than Meets the Eye

Finding a crystal is easy, as many tourists, students and locals can attest. The mine operator takes these novice diamond hunters to a pile of rocks and lets them break them up with a hammer. They invariably find crystals. If it rained recently, they may find crystals—sparkling in the sunshine—while walking around the quarry.





One of the easiest ways to find crystals is

to dig through and break up quarried rock.




Finding a vug loaded with big, clear, perfectly shaped crystals is another matter entirely. That’s the stuff of serious hard-rock miners. They rent a piece of the wall, tie up a blue tarp to mark their claim, and provide cover from rain, sun and prying eyes. They use hammers, sledges, star drills, and wedges made from car and truck leaf-springs, to chop out a section of dolostone. From time to time they tap on the wall, listening for the all-inspiring hollow sound that indicates a vug that could be filled with crystals.

They come for a few days, a week, a month or the entire season (April-November). They pitch a tent, or park a trailer or motorhome at a campsite, or rent rooms and apartments in nearby villages. They become part of the community of miners that migrate to the Mohawk Valley each year from throughout the country and around the world…to discover Herkimer Diamonds.


Where to Find Mohawk Valley Crystals

There are no secrets to finding Mohawk Valley Crystals. The mine operators and most miners are happy to share information and techniques. Mining tools can be rented or purchased, so miners can dig diamonds from rocks or from the wall.


Ace of Diamonds Mine & Campground – NYS Route 28, Box 505, Middleville, NY 13406 (315) 891-3855 or 891-3896


Herkimer Diamond Mines Resort and KOA Kampground

Physical Address: Route 28 North, Herkimer, NY

Mailing Address: 800 Mohawk Street, Herkimer, NY 13350

KOA Reservations: 1-800-562-0897

Herkimer Diamond Corporate Office: 1-866-717-GEMS ext. 105

FAX #315-717-0066 http://www.herkimerdiamond.com/


Treasure Mountain Diamond Mine -1959 State Route 5S Little Falls. NY 13365 (315)-823-7625 http://treasuremt.com


Crystal Grove Diamond Mine and Campground – 161 County Highway 114, St. Johnsville, NY 13452: (518) 568-2914 http://www.crystalgrove.com