Tiragalloite is a rare manganese arsenic silicate primarily known from the Gambatesa mine in Italy. It typically occurs as small orange tabular crystals and is highly prized by collectors of rare mineral species due to its restricted locality and complex chemistry.
Is this tiragalloite?
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 tiragalloite with a known reference. Tiragalloite sits at Mohs 4-5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Tiragalloite leaves a yellowish-orange streak.
- 3Read the lusterHold the specimen under a strong light. Tiragalloite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: orange, reddish-orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, massive, granular.
Often confused with
Tiragalloite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Tiragalloite leaves yellowish-orange, Bustamite leaves white; luster reads vitreous on Tiragalloite and vitreous to pearly on Bustamite.
How to tell apart: Streak differs — Tiragalloite leaves yellowish-orange, Rhodonite leaves white.
Often found alongside tiragalloite
Minerals reported to co-occur with tiragalloite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn₄AsSi₃O₁₂(OH)
- Mohs hardness
- 4-5
- Density
- 3.84 g/cm³
- Colors
- Streak
- Yellowish-orange
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Massive, Granular
- Cleavage
- Good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Manganese-rich Hydrothermal Deposits
- Typical price
- $100-500 thumbnail size
Where rockhounds find tiragalloite
Classic worldwide localities
- Gambatesa mine, Liguria, Italy
Field-hunting tip
Look in manganese-rich hydrothermal deposits country — that is the host setting where tiragalloite typically forms. If you start seeing braunite, quartz, saneroite in float, you are in the right ground. Field specimens usually show a tabular crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find tiragalloite on the map
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