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. Streak: colorless to pale yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to pearly.
- 4Match the color rangeCompare against the expected color range: brown, pale golden 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□)CaFe₇Ti₂(Si₄O₁₂)₂O₂(OH)₅
- Mohs hardness
- 3
- Density
- 3.263 g/cm³
- Colors
- BrownPale golden brown
- Streak
- Colorless to pale yellow
- Luster
- Vitreous to pearly
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Tabular crystals
- Cleavage
- Perfect on {001}, moderate on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In pegmatite veins and fenite associated with alkaline granitic massifs
Where rockhounds find tarbagataite
Classic worldwide localities
- Verkhnee Espe deposit, northern part of the Tarbagatai mountain range, Akjailyautas Mountains, Kazakhstan
Field-hunting tip
Where it forms: In pegmatite veins and fenite associated with alkaline granitic massifs. If you start seeing astrophyllite, microcline, albite 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 tarbagataite?+
Where is tarbagataite found?+
What rocks look like tarbagataite?+
What minerals are found with tarbagataite?+
What kind of rock does tarbagataite form in?+
What is tarbagataite used for?+
Find tarbagataite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
