Wrightite is a very rare potassium aluminum titanium arsenate found as a primary mineral in high-temperature volcanic fumaroles. It typically occurs as small, pale yellow tabular crystals embedded in volcanic sublimation crusts. It is named in honor of Fred Eugene Wright, a renowned American petrologist and mineralogist.
Is this wrightite?
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 wrightite with a known reference. Wrightite sits at Mohs 3-3.5, 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: colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular crystals.
Often confused with
Wrightite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Wrightite is noticeably harder (Mohs 3-3.5 vs. 2); streak differs, so Wrightite leaves white, Tolbachite leaves yellowish red; luster reads vitreous on Wrightite and pearly on Tolbachite.
How to tell apart: Streak differs, so Wrightite leaves white, Euchroite leaves green.
Often found alongside wrightite
Minerals reported to co-occur with wrightite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₂Al₂O(AsO₄)₂
- Mohs hardness
- 3-3.5
- Density
- 3.50 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As sublimates on basaltic scoria near a volcanic fumarole vent (500-6000 °C.)
Where rockhounds find wrightite
Classic worldwide localities
- Second scoria cone, Tolbachik volcano, Kamchatka Peninsula, Russia
Field-hunting tip
Where it forms: As sublimates on basaltic scoria near a volcanic fumarole vent (500-6000 °C.). If you start seeing sylvite, ponomarevite, piypite in float, you are in the right ground. Typical habit: tabular crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify wrightite?+
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Find wrightite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
