Tarbagataite is a rare member of the eudialyte group typically found in alkaline pegmatites. It forms small, tabular, yellow-to-brown crystals often associated with microcline and aegirine in agpaitic environments.
Is this tarbagataite?
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 tarbagataite with a known reference. Tarbagataite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Tarbagataite leaves a colorless to pale yellow streak.
- 3Read the lusterHold the specimen under a strong light. Tarbagataite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellow-brown, brown.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular crystals.
Often confused with
Tarbagataite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Eudialyte is the harder of the two (Mohs 5-6 vs. 3); streak differs, so Tarbagataite leaves colorless to pale yellow, Eudialyte leaves white.
How to tell apart: Kentbrooksite is the harder of the two (Mohs 5-6 vs. 3); streak differs, so Tarbagataite leaves colorless to pale yellow, Kentbrooksite leaves white.
Often found alongside tarbagataite
Minerals reported to co-occur with tarbagataite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (K,Na,Sr)₄Zr₂TiSi₈O₂₂F₂·H₂O
- Mohs hardness
- 3
- Density
- 2.95-3.00 g/cm³
- Colors
- Streak
- Colorless to Pale Yellow
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Tabular Crystals
- Cleavage
- Perfect On {001}, Moderate On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Alkaline Pegmatites
Where rockhounds find tarbagataite
Classic worldwide localities
- Tarbagatai Mountains, Kazakhstan
Field-hunting tip
Look in alkaline pegmatites country, the host setting where tarbagataite typically forms. If you start seeing microcline, aegirine, arfvedsonite 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 tarbagataite on the map
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