Achalaite is an extremely rare iron-rich niobate mineral typically found in the pegmatites of the Achala batholith in Argentina. It occurs as small, dark prismatic crystals that are frequently confused with other members of the columbite-tapiolite group due to their similar physical appearance. Collectors typically acquire these only as specialized micromounts or rare thumbnail specimens from its type locality.
Is this achalaite?
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 achalaite with a known reference. Achalaite sits at Mohs 5.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, grains.
Often confused with
Achalaite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside achalaite
Minerals reported to co-occur with achalaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- FeTiNb₂O₈
- Mohs hardness
- 5.5
- Density
- 6.285 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In the intermediate zone of a topaz- and columbite-tantalite-bearing granitic pegmatite which is concordant with the schistosity of regional metasedimentary rocks
Where rockhounds find achalaite
Classic worldwide localities
- La Calandria granitic pegmatite, Cañada del Puerto, Córdoba province, Argentina
Field-hunting tip
Where it forms: In the intermediate zone of a topaz- and columbite-tantalite-bearing granitic pegmatite which is concordant with the schistosity of regional metasedimentary rocks. If you start seeing ta-rich rutile, pyrochlore supergroup minerals, cassiterite in float, you are in the right ground. Typical habit: prismatic crystals, grains. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify achalaite?+
Where is achalaite found?+
What rocks look like achalaite?+
What minerals are found with achalaite?+
What kind of rock does achalaite form in?+
What is achalaite used for?+
Find achalaite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
