Nesquehonite is a rare magnesium carbonate mineral that typically forms as white, radiating clusters or crusts in the vicinity of serpentinite or within coal mine tailings. Collectors should look for delicate, needle-like crystals that often occur as a secondary alteration product of other magnesium minerals.
Is this nesquehonite?
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 nesquehonite with a known reference. Nesquehonite 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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to slightly greasy.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic, radial.
Often confused with
Nesquehonite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside nesquehonite
Minerals reported to co-occur with nesquehonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg(HCO₃)(OH)·2H₂O
- Mohs hardness
- 2.5
- Density
- 1.824-1.854 g/cm³
- Streak
- White
- Luster
- Vitreous to slightly greasy
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic, radial
- Cleavage
- Perfect on {101}; good on {010}
- Rarity
- Uncommon
- Uses
- Collector, Scientific research
- Host rock
- Typically recently formed under near-surface conditions, as efflorescences in coal mines; in fractures in serpentinites; deposits around springs; in caves due to loss of CO2 in waters
Where rockhounds find nesquehonite
Classic worldwide localities
- Nesquehoning, near Lansford, Carbon Co., Pennsylvania, USA
- Robinson Gulch pegmatite, Jefferson Co., Colorado, USA
- Rapid Creek, Yukon Territory, Canada
- A coal mine at Lamure, Isère, and from Restivalgues, near Salers, Cantal, France
- Kraubath, Styria, Austria
- Rain, Taufers, Tirol, Italy
Field-hunting tip
Where it forms: Typically recently formed under near-surface conditions, as efflorescences in coal mines; in fractures in serpentinites; deposits around springs; in caves due to loss of CO2 in waters. If you start seeing lansfordite, dypingite, calcite in float, you are in the right ground. Typical habit: prismatic, radial. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify nesquehonite?+
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What rocks look like nesquehonite?+
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Find nesquehonite on the map
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