Hydrombobomkulite is a rare hydrated nickel-aluminum nitrate sulfate carbonate mineral belonging to the layered double hydroxide group. It typically occurs as small, delicate platy crystals or thin crusts in the oxidation zones of nickel-bearing mineral deposits.

Hardness

Mohs

Luster

Pearly

Streak

Light blue

Transparency

Translucent

mineralrareHydrotalcite Group family

Hydrombobomkulite

Hardness: 2
Luster: Pearly
Streak: Light blue
Transparency: Translucent

No image

Is this hydrombobomkulite?

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 hydrombobomkulite with a known reference. Hydrombobomkulite 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. Streak: light blue.
3
Read the luster
Hold the specimen under a strong light. Luster: pearly.
4
Match the color range
Compare against the expected color range: sky blue.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: nodular, powdery.

Often confused with

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

mineral

Hydrotalcite

Mohs 2

How to tell apart: Streak differs, so Hydrombobomkulite leaves light blue, Hydrotalcite leaves white; luster reads pearly on Hydrombobomkulite and satiny to greasy or waxy on Hydrotalcite.

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Often found alongside hydrombobomkulite

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

All properties

Chemical formula: NiAl₄(NO₃)₂(OH)₁₂(H₂O)₁₄
Mohs hardness: 2
Density: 2.28 g/cm³
Colors: Sky blue
Streak: Light blue
Luster: Pearly
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Nodular, powdery
Cleavage: On {001}, perfect
Rarity: Rare
Uses: Collector
Host rock: By the interaction of solutions of nickel sulfate from weathering Cu–Ni-bearing sulfides with aluminosilicate minerals and nitrate derived from bat guano (Mbobo Mkulu Cave, South Africa)

Where rockhounds find hydrombobomkulite

Classic worldwide localities

Jomac mine, White Canyon district, San Juan Co., Utah, USA
Mbobo Mkulu Cave, near Ngodwana, Eastern Transvaal, South Africa

Field-hunting tip

Where it forms: By the interaction of solutions of nickel sulfate from weathering Cu–Ni-bearing sulfides with aluminosilicate minerals and nitrate derived from bat guano (Mbobo Mkulu Cave, South Africa). If you start seeing allophane, mbobomkulite, chalcoalumite in float, you are in the right ground. Typical habit: nodular, powdery. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify hydrombobomkulite?+

Mohs hardness is 2. Luster: pearly. The streak is light blue. Common colors include sky blue.

Where is hydrombobomkulite found?+

Notable localities include Jomac mine, White Canyon district, San Juan Co., Utah, USA; Mbobo Mkulu Cave, near Ngodwana, Eastern Transvaal, South Africa.

Is hydrombobomkulite safe to handle?+

Hydrombobomkulite contains nickel. Contains nickel, which is a known skin sensitizer and potentially toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid creating dust.

What rocks look like hydrombobomkulite?+

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

What minerals are found with hydrombobomkulite?+

Hydrombobomkulite commonly co-occurs with Allophane, Mbobomkulite, Chalcoalumite, Oswaldpeetersite, Cuprite, Antlerite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does hydrombobomkulite form in?+

Where it forms: By the interaction of solutions of nickel sulfate from weathering Cu–Ni-bearing sulfides with aluminosilicate minerals and nitrate derived from bat guano (Mbobo Mkulu Cave, South Africa). Working float back to the host body is the standard way to chase a fresh occurrence.

What is hydrombobomkulite used for?+

Hydrombobomkulite is used in collector.

Find hydrombobomkulite on the map

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