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 6-6.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Achalaite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Achalaite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black, brownish-black.
- 5Look at form & habitCrystal system: tetragonal. 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
- Fe²⁺Fe³⁺Nb₂O₈
- Mohs hardness
- 6-6.5
- Density
- 7.35 g/cm³
- Colors
- Streak
- Black
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Prismatic Crystals, Grains
- Cleavage
- Distinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- $50-300+ depending on crystal size and specimen quality
Where rockhounds find achalaite
Classic worldwide localities
- Achala batholith, Argentina
Field-hunting tip
Look in granite pegmatites country — that is the host setting where achalaite typically forms. If you start seeing quartz, microcline, albite in float, you are in the right ground. Field specimens usually show a prismatic crystals, grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify achalaite?+
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How much is achalaite worth?+
What rocks look like achalaite?+
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Find achalaite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
