Nahcolite is a natural form of sodium bicarbonate that typically occurs in saline evaporite deposits. It is often found as transparent to white crystals or crusts and is highly soluble in water, meaning collectors should store it in a dry environment. It is most famously associated with the Green River Formation, where it occurs in significant beds alongside other evaporite minerals.
Is this nahcolite?
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 nahcolite with a known reference. Nahcolite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Nahcolite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Nahcolite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, gray, yellowish.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, fibrous, tabular, botryoidal crusts.
Often confused with
Nahcolite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside nahcolite
Minerals reported to co-occur with nahcolite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaHCO₃
- Mohs hardness
- 2.5
- Density
- 2.2 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Fibrous, Tabular, Botryoidal Crusts
- Cleavage
- Perfect
- Rarity
- Uncommon
- Uses
- Collector, Industrial, Research
- Host rock
- Evaporite Deposits, Saline Lake Beds
- Typical price
- $10-60 for small representative specimens
Where rockhounds find nahcolite
Classic worldwide localities
- Green River Formation, Colorado, USA
- Searles Lake, California, USA
- Vesuvius, Italy
- Natron Valley, Egypt
Field-hunting tip
Look in evaporite deposits, saline lake beds country — that is the host setting where nahcolite typically forms. If you start seeing trona, halite, thermonatrite in float, you are in the right ground. Field specimens usually show a prismatic crystals, fibrous, tabular, botryoidal crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find nahcolite on the map
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