Specimen at a glance
| Mineral | Quartz (var. Herkimer diamond) |
|---|---|
| Chemistry | SiO2 |
| Mohs hardness | 7 |
| Crystal system | Trigonal |
| Locality | Herkimer, New York |
| You receive | The exact specimen pictured |
About this specimen
A striking double-terminated Herkimer diamond quartz specimen from Herkimer Mountain, New York, collected in June of 2025. True Herkimer diamonds are not diamonds at all, but a uniquely clear and lustrous variety of quartz found almost exclusively within dolomite host rock in Herkimer County — a geologic accident of timing and chemistry that has made this region world-famous among mineral collectors since the 18th century. What sets Herkimer diamonds apart is their naturally occurring double termination: because the crystals grow freely within soft pockets in the dolomite rather than attached to a rock face, they develop pointed faces on both ends. This particular piece carries warm smoky and champagne tones through its faces along with the sharp, high-luster crystal edges that define genuine Herkimer material, and shows excellent transparency where light passes through its termination points. Herkimer diamonds are prized not just for their gemmy clarity but for their history — miners have worked these dolomite quarries for generations, and each true Herkimer carries the story of that particular pocket. A wonderful centerpiece specimen for any quartz or New York locality collection.
Herkimer diamond quartz: the science
- They grew floating in pockets rather than attached to rock, so many formed points on both ends: 18 natural faces with no cutting or polishing.
- The black specks inside are anthraxolite, a solidified hydrocarbon. Researchers describe the mining district as essentially a fossilized oil field.
- The host rock is about 500 million years old, but the quartz grew much later, during the Carboniferous, when mineral-rich basin fluids moved through the dolostone.
Go deeper
Want the full story on Herkimer diamond quartz: how it forms, how to identify it, and what makes a great specimen?
Read Herkimer Diamonds: The Complete Guide Shop all Herkimer Diamond Quartz
Questions about this piece
What is Herkimer diamond quartz?
Herkimer diamonds are not diamonds. They are exceptionally clear, naturally double-terminated quartz crystals that grew loose inside cavities in the Late Cambrian Little Falls Dolostone of New York’s Mohawk Valley.
Where was it found?
This piece comes from Herkimer, New York. We list a locality whenever it is known, because where a mineral formed is part of its story and its value.
How hard is it, and how should I care for it?
It rates 7 on the Mohs scale. At Mohs 7 it is durable, but points and edges chip if they knock against other quartz. Store it separately, rinse in lukewarm water, and keep it away from ultrasonic cleaners and sudden heat.
Is this the exact piece I will receive?
Yes. This listing was photographed individually, and you receive the exact piece shown in the photos.
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