Mbobomkulite is a rare nickel-aluminum sulfate-nitrate hydroxide mineral typically found as a secondary mineral in oxidized nickel ore zones. It forms distinctive blue, pearly, platy aggregates that are often fragile and delicate for collectors to handle.
Is this mbobomkulite?
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 mbobomkulite with a known reference. Mbobomkulite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light blue.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly.
- 4Match the color rangeCompare against the expected color range: sky blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: nodular, powdery.
Often confused with
Mbobomkulite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside mbobomkulite
Minerals reported to co-occur with mbobomkulite. 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)₃
- Mohs hardness
- 2
- Density
- 2.30 g/cm³
- Colors
- Streak
- Light blue
- Luster
- Pearly
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Nodular, powdery
- Cleavage
- On {001}, perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare product of oxidation and leaching of Ni–Cu from sulfides in the cave roof, reacting with aluminum from phyllosilicates and nitrate from bat guano (Mbobo Mkulu Cave, South Africa)
Where rockhounds find mbobomkulite
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: A rare product of oxidation and leaching of Ni–Cu from sulfides in the cave roof, reacting with aluminum from phyllosilicates and nitrate from bat guano (Mbobo Mkulu Cave, South Africa). If you start seeing allophane, chalcoalumite, hydrombobomkulite 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 mbobomkulite?+
Where is mbobomkulite found?+
Is mbobomkulite safe to handle?+
What rocks look like mbobomkulite?+
What minerals are found with mbobomkulite?+
What kind of rock does mbobomkulite form in?+
What is mbobomkulite used for?+
Find mbobomkulite on the map
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