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. Wrightite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Wrightite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellowish-brown.
- 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 yellow, Tolbachite leaves yellowish red; luster reads vitreous on Wrightite and subadamantine on Tolbachite.
How to tell apart: Streak differs, so Wrightite leaves yellow, Euchroite leaves pale 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
- K₂Al₂Ti₂O₂(AsO₄)₄
- Mohs hardness
- 3-3.5
- Density
- 3.37 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Fumarolic Deposits
- Typical price
- $200-800 per specimen
Where rockhounds find wrightite
Classic worldwide localities
- La Fossa crater, Vulcano, Aeolian Islands, Italy
Field-hunting tip
Look in fumarolic deposits country, the host setting where wrightite typically forms. If you start seeing arsenohauchecornite, realgar, anhydrite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find wrightite on the map
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