Symplesite is a secondary mineral typically formed by the oxidation of arsenic-bearing minerals like arsenopyrite. It is often found as delicate, prismatic blue-green crystals or fibrous radial aggregates, resembling the related mineral vivianite.
Is this symplesite?
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 symplesite with a known reference. Symplesite 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: pale bluish.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to oily, pearly on cleavages.
- 4Match the color rangeCompare against the expected color range: blue, greenish black, gray green, light blue, light green.
- 5Look at form & habitCrystal system: triclinic. Typical habit: crystalline, earthy, prismatic.
Often confused with
Symplesite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Symplesite leaves pale bluish, Vivianite leaves white, altering to dark blue, brown.
How to tell apart: Luster reads vitreous to oily, pearly on cleavages on Symplesite and subadamantine, pearly on cleavages on Erythrite.
Often found alongside symplesite
Minerals reported to co-occur with symplesite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe₃(AsO₄)₂·8H₂O
- Mohs hardness
- ~2.5
- Density
- 2.96-3.01 g/cm³
- Streak
- Pale bluish
- Luster
- Vitreous to oily, pearly on cleavages
- Transparency
- Transparent, becoming translucent on oxidation
- Crystal system
- Triclinic
- Crystal habit
- Crystalline, earthy, prismatic
- Cleavage
- On {110}, perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral in the oxidized zone of some arsenic-rich hydrothermal mineral deposits
Where rockhounds find symplesite
Classic worldwide localities
- Kalkar quarry, Santa Cruz, Santa Cruz Co., California, USA
- Getchell mine, about 32 km northeast of Golconda, Humboldt Co., Nevada, USA
- Custer Mountain quarry, Custer, Custer Co., North Dakota, USA
- Tännig, near Lobenstein, Thuringia, and at Neustädtel-Schneeberg, Saxony, Germany
- Baia Sprie (Felsőbánya), Romania
- Pisek, Czech Republic
Field-hunting tip
Where it forms: A rare secondary mineral in the oxidized zone of some arsenic-rich hydrothermal mineral deposits. If you start seeing pharmacosiderite, scorodite, erythrite in float, you are in the right ground. Typical habit: crystalline, earthy, prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify symplesite?+
Where is symplesite found?+
Is symplesite safe to handle?+
What rocks look like symplesite?+
What minerals are found with symplesite?+
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Find symplesite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
