Fluckite is a rare calcium manganese arsenate mineral that typically forms delicate, needle-like white or pinkish crystals. It is primarily sought after by advanced collectors for its aesthetic crystal clusters found in historic mining districts in Europe. Due to its arsenic content, it should be handled and stored with appropriate safety precautions.
Is this fluckite?
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 fluckite with a known reference. Fluckite sits at Mohs 3.5-4, 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.
- 4Match the color rangeCompare against the expected color range: colorless, light pink, dark pink.
- 5Look at form & habitCrystal system: triclinic. Typical habit: aggregates, prismatic, radial.
Often confused with
Fluckite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Fluckite is noticeably harder (Mohs 3.5-4 vs. 2.5); streak differs, so Fluckite leaves white, Pharmacosiderite leaves yellowish green; luster reads vitreous on Fluckite and adamantine to greasy on Pharmacosiderite.
How to tell apart: Fluckite is noticeably harder (Mohs 3.5-4 vs. 2-2.5).
Often found alongside fluckite
Minerals reported to co-occur with fluckite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMn(AsO₃OH)₂·2H₂O
- Mohs hardness
- 3.5-4
- Density
- 3.05 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Triclinic
- Crystal habit
- Aggregates, prismatic, radial
- Cleavage
- On {010}, perfect; on {100}, easy; on {101}, imperfect and difficult
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A post-mine low-temperature reaction product of carbonate gangue with arsenical solutions derived from arsenic (Gabe-Gottes mine, France)
Where rockhounds find fluckite
Classic worldwide localities
- Sterling Hill, Ogdensburg, Sussex Co., New Jersey, USA
- Gabe-Gottes mine, Rauenthal, near Sainte-Marie-aux-Mines, Haut Rhin, France
Field-hunting tip
Where it forms: A post-mine low-temperature reaction product of carbonate gangue with arsenical solutions derived from arsenic (Gabe-Gottes mine, France). If you start seeing arsenic, tennantite, skutterudite in float, you are in the right ground. Typical habit: aggregates, prismatic, radial. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify fluckite?+
Where is fluckite found?+
Is fluckite safe to handle?+
What rocks look like fluckite?+
What minerals are found with fluckite?+
What kind of rock does fluckite form in?+
What is fluckite used for?+
Find fluckite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
