Wiserite is a rare manganese borate mineral typically found as radial or fibrous aggregates within dolomitic marbles. It is highly prized by collectors for its distinct yellow-to-brown coloration and notable fluorescence under ultraviolet light. It is almost exclusively found at its type locality in the Binntal region of Switzerland.
Is this wiserite?
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 wiserite with a known reference. Wiserite 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.
- 4Match the color rangeCompare against the expected color range: white, brownish, reddish, pinkish brown.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: fibrous, prismatic, radial aggregates.
Often confused with
Wiserite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Ludwigite is the harder of the two (Mohs 5-5.5 vs. 2.5); streak differs, so Wiserite leaves white, Ludwigite leaves black to greenish black; luster reads vitreous on Wiserite and submetallic on Ludwigite.
How to tell apart: Luster reads vitreous on Wiserite and silky, dull, earthy on Sussexite.
Often found alongside wiserite
Minerals reported to co-occur with wiserite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn₁₄(B₂O₅)₄(OH)₈·(Si,Mg)(O,OH)₄Cl
- Mohs hardness
- 2.5
- Density
- 3.54 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Tetragonal
- Crystal habit
- Fibrous, prismatic, radial aggregates
- Cleavage
- None
- Fluorescence
- Bright yellow under UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An accessory mineral in stratiform manganese deposits
Where rockhounds find wiserite
Classic worldwide localities
- Gonzen mine, near Sargans, St. Gallen, Switzerland
- Kombat mine, 49 km south of Tsumeb, Namibia
- Yaei mine, Tsuchiyama, Shiga Prefecture, Japan
- Kaso mine, Tochigi Prefecture, Japan
- Azuma, Nakanoyama, and Rito mines, Gumma Prefecture, Japan
Field-hunting tip
Where it forms: An accessory mineral in stratiform manganese deposits. If you start seeing hausmannite, jacobsite, alleghanyite in float, you are in the right ground. Typical habit: fibrous, prismatic, radial aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
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Find wiserite on the map
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