Tuhualite is an extremely rare cyclosilicate mineral typically found in volcanic rocks. It is most famous for its distinctive deep violet-blue color and tabular habit, primarily occurring in specific peralkaline rhyolite deposits.
Is this tuhualite?
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 tuhualite with a known reference. Tuhualite sits at Mohs 4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Tuhualite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Tuhualite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: deep blue, violet-blue, purple.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular crystals, massive.
Often confused with
Tuhualite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Osumilite is the harder of the two (Mohs 5-5.5 vs. 4).
How to tell apart: Milarite is the harder of the two (Mohs 5.5-6 vs. 4).
How to tell apart: Cordierite is the harder of the two (Mohs 7-7.5 vs. 4).
Often found alongside tuhualite
Minerals reported to co-occur with tuhualite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Na,K)Fe²⁺₂Fe³⁺₂Si₁₂O₃₀
- Mohs hardness
- 4
- Density
- 2.92 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular Crystals, Massive
- Cleavage
- Poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Peralkaline Rhyolitic Volcanic Rocks
- Typical price
- $100-500 per specimen
Where rockhounds find tuhualite
Classic worldwide localities
- Mayor Island, New Zealand
- Eifel region, Germany
Field-hunting tip
Look in peralkaline rhyolitic volcanic rocks country — that is the host setting where tuhualite typically forms. If you start seeing aegirine, arfvedsonite, quartz in float, you are in the right ground. Field specimens usually show a tabular crystals, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify tuhualite?+
Where is tuhualite found?+
How much is tuhualite worth?+
What rocks look like tuhualite?+
What minerals are found with tuhualite?+
What kind of rock does tuhualite form in?+
What is tuhualite used for?+
Find tuhualite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
