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Tarapacáite is a rare potassium chromate mineral primarily found in the hyper-arid regions of Chile. It typically forms small, yellow, tabular crystals or crusts within nitrate-rich evaporite deposits and is highly soluble in water.

Hardness
2
Mohs
Luster
Vitreous
Streak
Yellow
Transparency
Transparent

Is this tarapacáite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

  • 1
    Test the hardness
    Try to scratch tarapacáite with a known reference. Tarapacáite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
  • 2
    Check the streak
    Drag the specimen across an unglazed porcelain plate. Tarapacáite leaves a yellow streak.
  • 3
    Read the luster
    Hold the specimen under a strong light. Tarapacáite typically shows a vitreous luster.
  • 4
    Match the color range
    Compare against the expected color range: yellow, orange-yellow.
  • 5
    Look at form & habit
    Crystal system: orthorhombic. Typical habit: tabular crystals, massive, crusts.

Often confused with

Tarapacáite vs. its common look-alikes, and how to tell them apart in the field.

Crocoite mineral
mineral
Crocoite
Mohs 2.5-3

How to tell apart: Streak differs, so Tarapacáite leaves yellow, Crocoite leaves orange-yellow; luster reads vitreous on Tarapacáite and adamantine on Crocoite.

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Often found alongside tarapacáite

Minerals reported to co-occur with tarapacáite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula
K₂CrO₄
Mohs hardness
2
Density
2.71 g/cm³
Colors
YellowOrange-yellow
Streak
Yellow
Luster
Vitreous
Transparency
Transparent
Crystal system
Orthorhombic
Crystal habit
Tabular Crystals, Massive, Crusts
Cleavage
Perfect
Rarity
Rare
Uses
Collector
Host rock
Arid Evaporite Deposits
Typical price
$50-300 per specimen

Where rockhounds find tarapacáite

Classic worldwide localities

  • Tarapacá, Chile
  • Atacama Desert, Chile

Field-hunting tip

Look in arid evaporite deposits country, the host setting where tarapacáite typically forms. If you start seeing dietzeite, nitratine, gypsum in float, you are in the right ground. Field specimens usually show a tabular crystals, massive, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify tarapacáite?+
Mohs hardness is 2. It typically shows a vitreous luster. The streak is yellow. Common colors include yellow, orange-yellow.
Where is tarapacáite found?+
Notable localities include Tarapacá, Chile; Atacama Desert, Chile.
How much is tarapacáite worth?+
Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.
Is tarapacáite safe to handle?+
It contains toxic constituents. Contains chromium in the hexavalent state, which is toxic and a known carcinogen. Wash hands thoroughly after handling and avoid inhaling dust. Handle with care, avoid grinding or breathing dust, and store separately.
What rocks look like tarapacáite?+
Tarapacáite is most often confused with Crocoite. A quick hardness test and a streak check separate the look-alikes faster than color alone.
What minerals are found with tarapacáite?+
Tarapacáite commonly co-occurs with Dietzeite, Nitratine, Gypsum, Halite. Spotting any of these in float or country rock is a useful trip signal.
What kind of rock does tarapacáite form in?+
Tarapacáite typically forms in arid evaporite deposits. Working float back to the host body is the standard way to chase a fresh occurrence.
What is tarapacáite used for?+
Tarapacáite is used in collector.

Find tarapacáite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.

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