Why hunt for “Herkimer diamonds”? It’s great fun and every time you break open a rock you will look with anticipation to see if you liberated an unseen quartz crystal. Nice “Herkimer diamonds” are highly prized mineral specimens and are sought by mineral collectors worldwide. Large numbers of Herkimer crystals are also used in jewelry…

The name “Herkimer diamond” is a misnomer. A misnomer is a name that is intentionally or inadvertently incorrect. It is incorrect because the crystals called “Herkimer diamonds” are quartz crystals rather than diamond crystals. The name “Herkimer diamonds” has been used for over 100 years and is deeply ingrained in the language of local people as well…

For finding large quantities of crystals, the most successful mining method is to break into large cavities in the quarry walls and floors using sledge hammers and wedges (power equipment is not permitted at the mines listed in this article). This method requires tools, patience, time, and a knowledge of how to break an extremely…

Some visitors to the mines have been successful by simply searching the rock rubble for exposed crystals or searching the quarry floor for loose crystals. We found several really nice crystals this way and lots of tiny ones. We have also seen children find many nice crystals this way. This is the safest prospecting method,…

The easy way to prospect is to find pieces of vuggy rock and break them open with a heavy hammer. Usually any vugs found will be empty, but if you are lucky, the rock will break to reveal one or several “Herkimer diamonds” within a cavity. If your visit to the mine will last just a…

The key to finding “Herkimer diamonds” is a knowledge that they occur in cavities (vugs) within the Little Falls Dolostone (see photo above). These cavities can be smaller than a pea or several feet across. At both of the mines listed above, the Little Falls Dolostone is exposed at the surface, and a significant amount…

Some of the best places to find “Herkimer diamonds” today are located along New York State Routes 28 and 29 near Middleville, New York. (When visiting this area it is important to remember that all land in New York either belongs to the government or is private property. Collecting minerals from government lands is illegal…

“Herkimer diamonds” share most of the physical properties of other forms of quartz. They are almost always transparent and range from colorless to smoky in color. “Herkimer diamonds” are, by definition, doubly terminated; however, they are known to occur in a wide range of crystal forms (see illustration). The crystals contain a wide range of inclusions.…

The “Herkimer diamonds” of New York are not a recent discovery. The Mohawk people and early settlers knew about the crystals. They found them in stream sediments and plowed fields. They were amazed with the crystals and immediately held them in high esteem. People used the crystals as amulets, used them to make tools, and…

The host rock of “Herkimer diamonds” is the Cambrian-age, Little Falls Dolostone. The Little Falls Dolostone was deposited about 500 million years ago, and the “Herkimer diamonds” formed in cavities within the dolostone. These cavities are frequently lined with drusy quartz crystals and are often coated with a tarry hydrocarbon. Although Herkimer County, New York is…