Betpakdalite-CaCa is a rare secondary molybdenum arsenate mineral typically occurring in the oxidation zones of ore deposits. It is often found as small, fragile, yellow platy crystals or as earthy, powdery coatings on host rocks.

Hardness

Mohs

Luster

Dull to waxy

Streak

Pale yellow

Transparency

Transparent

mineralrareBetpakdalite Group family

Betpakdalite-CaCa

Hardness: ~3
Luster: Dull to waxy
Streak: Pale yellow
Transparency: Transparent

Is this betpakdalite-caca?

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 betpakdalite-caca with a known reference. Betpakdalite-CaCa sits at Mohs ~3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: pale yellow.
3
Read the luster
Hold the specimen under a strong light. Luster: dull to waxy.
4
Match the color range
Compare against the expected color range: rarely brownish, tint.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy crystals, powdery aggregates.

Often confused with

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

mineral

Manganberzeliite

Mohs 4.5-5

How to tell apart: Manganberzeliite is the harder of the two (Mohs 4.5-5 vs. ~3); streak differs, so Betpakdalite-CaCa leaves pale yellow, Manganberzeliite leaves white to yellow-orange; luster reads dull to waxy on Betpakdalite-CaCa and resinous on Manganberzeliite.

Compare →

Often found alongside betpakdalite-caca

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

All properties

Chemical formula: [Ca₂(H₂O)₁₇Ca(H₂O)₆][Mo₈As₂Fe₃O₃₆(OH)]
Mohs hardness: ~3
Density: 2.98-3.05 g/cm³
Colors: Rarely brownishTint
Streak: Pale yellow
Luster: Dull to waxy
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Platy crystals, powdery aggregates
Cleavage: {001}, very good
Rarity: Rare
Uses: Collector
Host rock: Filling cracks in leached pyrite in the oxidized zone of a mineral deposit (Kara-Oba deposit, Kazakhstan); on vein quartz (Krupka, Czech Republic)

Where rockhounds find betpakdalite-caca

Classic worldwide localities

Kara-Oba Mo-W deposit, Bet-Pak-Dal Desert, central Kazakhstan
Descubridora mine, Pampa Larga district, Copiapó, Chile, Norway
Bajan Cogto, Mongolia, Norway
Rustler mine, Gold Hill district, Tooele County, Utah, USA, Norway
Nedre Kvartsen quarry, Drag, Tysfjord, Nordland, Norway
Krupka, Krušné hory Mountains, Czech Republic

Field-hunting tip

Where it forms: Filling cracks in leached pyrite in the oxidized zone of a mineral deposit (Kara-Oba deposit, Kazakhstan); on vein quartz (Krupka, Czech Republic). If you start seeing ferrimolybdite, gypsum, jarosite in float, you are in the right ground. Typical habit: platy crystals, powdery aggregates. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify betpakdalite-caca?+

Mohs hardness is ~3. Luster: dull to waxy. The streak is pale yellow. Common colors include rarely brownish, tint.

Where is betpakdalite-caca found?+

Notable localities include Kara-Oba Mo-W deposit, Bet-Pak-Dal Desert, central Kazakhstan; Descubridora mine, Pampa Larga district, Copiapó, Chile, Norway; Bajan Cogto, Mongolia, Norway; Rustler mine, Gold Hill district, Tooele County, Utah, USA, Norway; Nedre Kvartsen quarry, Drag, Tysfjord, Nordland, Norway.

Is betpakdalite-caca safe to handle?+

Betpakdalite-CaCa contains arsenic and calls for real care. Contains arsenic, handle with care. Wash hands thoroughly after handling and avoid inhaling dust.

What rocks look like betpakdalite-caca?+

Betpakdalite-CaCa is most often confused with Manganberzeliite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with betpakdalite-caca?+

Betpakdalite-CaCa commonly co-occurs with Ferrimolybdite, Gypsum, Jarosite, Hydromica, Limonite, Opal. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does betpakdalite-caca form in?+

Where it forms: Filling cracks in leached pyrite in the oxidized zone of a mineral deposit (Kara-Oba deposit, Kazakhstan); on vein quartz (Krupka, Czech Republic). Working float back to the host body is the standard way to chase a fresh occurrence.

What is betpakdalite-caca used for?+

Betpakdalite-CaCa is used in collector.

Find betpakdalite-caca on the map

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