Tusionite is a rare manganese tin borate mineral typically found in granitic pegmatites. It forms glassy, rhombohedral crystals that are highly sought after by advanced collectors for their rarity and aesthetic appeal.
Is this tusionite?
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 tusionite with a known reference. Tusionite sits at Mohs 5-6, 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, yellow brown, light yellow.
- 5Look at form & habitCrystal system: trigonal. Typical habit: tabular to rhombohedral crystals.
Often confused with
Tusionite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside tusionite
Minerals reported to co-occur with tusionite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MnSn(BO₃)₂
- Mohs hardness
- 5-6
- Density
- 4.73 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Trigonal
- Crystal habit
- Tabular to rhombohedral crystals
- Cleavage
- Perfect on {0001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Of late-stage hydrothermal origin, rare in granite pegmatites, typically in miarolitic cavities
Where rockhounds find tusionite
Classic worldwide localities
- Belo Horizonte No. 1 and New Columbia No. 1 pegmatites, Thomas Mountain, Riverside Co., California, USA
- Upper Tusion River, Shakhdara Range, southwestern Pamir Mountains, Tadjikistan
- Řečice, Czech Republic
Field-hunting tip
Where it forms: Of late-stage hydrothermal origin, rare in granite pegmatites, typically in miarolitic cavities. If you start seeing tetrawickmanite, hambergite, danburite in float, you are in the right ground. Typical habit: tabular to rhombohedral crystals. Train your eye for that shape before scanning the outcrop.
Common questions
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Find tusionite on the map
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