Herkimer diamond is exceptionally clear, doubly terminated quartz crystals found in vugs within dolostone outcrops in New York. They are famous for their brilliant, diamond-like luster and natural geometric perfection that often requires no cutting or polishing. Collectors prize them for their extreme clarity and the occasional inclusion of black carbonaceous material or fluid pockets.
Is this herkimer diamond?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch herkimer diamond with a known reference. Herkimer Diamond sits at Mohs 7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Herkimer Diamond leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Herkimer Diamond typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, smoky.
- 5Look at form & habitCrystal system: trigonal. Typical habit: doubly terminated hexagonal prismatic.
Often confused with
Herkimer Diamond vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside herkimer diamond
Minerals reported to co-occur with herkimer diamond. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SiO₂
- Mohs hardness
- 7
- Density
- 2.65 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Doubly Terminated Hexagonal Prismatic
- Cleavage
- None
- Rarity
- Common
- Uses
- Collector, Jewelry, Lapidary
- Host rock
- Dolostone
- Typical price
- $5-50 for small specimens, $100-500+ for large gem-quality clusters
Where rockhounds find herkimer diamond
9 mapped spotsClassic worldwide localities
- Herkimer County, New York
- Little Falls, New York
- Mohawk Valley, New York
Field-hunting tip
Look in dolostone country — that is the host setting where herkimer diamond typically forms. If you start seeing dolomite, calcite, pyrite in float, you are in the right ground. Field specimens usually show a doubly terminated hexagonal prismatic habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in New York, Pennsylvania — start trip planning there.
Common questions
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Find herkimer diamond on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
