Pecos Diamonds are small, doubly terminated quartz crystals found in the gypsum and dolomite beds of the Pecos River Valley. They are known for their distinct shape which mimics gemstones, often occurring as loose, individual crystals weathered out of the surrounding sedimentary rock.
Is this pecos diamonds?
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 pecos diamonds with a known reference. Pecos Diamonds 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. Pecos Diamonds leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Pecos Diamonds typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: clear, colorless, red, brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: doubly terminated prismatic crystals.
Often confused with
Pecos Diamonds vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside pecos diamonds
Minerals reported to co-occur with pecos diamonds. 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 Prismatic Crystals
- Cleavage
- None
- Rarity
- Common
- Uses
- Collector, Lapidary
- Host rock
- Sedimentary Evaporite Deposits
- Typical price
- $5-50 thumbnail, $50-200 cluster
Where rockhounds find pecos diamonds
3 mapped spotsClassic worldwide localities
- Pecos River Valley, New Mexico, USA
- Eddy County, New Mexico, USA
- Chaves County, New Mexico, USA
Field-hunting tip
Look in sedimentary evaporite deposits country — that is the host setting where pecos diamonds typically forms. If you start seeing gypsum, dolomite, calcite in float, you are in the right ground. Field specimens usually show a doubly terminated prismatic crystals habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in New Mexico — start trip planning there.
Common questions
How do you identify pecos diamonds?+
Where is pecos diamonds found?+
Can I find pecos diamonds in the United States?+
How much is pecos diamonds worth?+
What rocks look like pecos diamonds?+
What minerals are found with pecos diamonds?+
What kind of rock does pecos diamonds form in?+
What is pecos diamonds used for?+
Find pecos diamonds on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
