Nickelaustinite is a rare arsenate mineral belonging to the adelite group, typically forming vibrant green crusts or small acicular crystal sprays in oxidized base metal deposits. It is best identified through mineral association in the Tsumeb or Ojuela mines, where it often coats other secondary minerals like smithsonite or calcite.
Is this nickelaustinite?
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 nickelaustinite with a known reference. Nickelaustinite sits at Mohs 4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: silky to subadamantine.
- 4Match the color rangeCompare against the expected color range: grass green, yellow green.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: crusts, botryoidal, acicular crystals.
Often confused with
Nickelaustinite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads silky to subadamantine on Nickelaustinite and subadamantine to silky in aggregates on Austinite.
How to tell apart: Streak differs, so Nickelaustinite leaves white, Conichalcite leaves green; luster reads silky to subadamantine on Nickelaustinite and vitreous to somewhat greasy on Conichalcite.
How to tell apart: Streak differs, so Nickelaustinite leaves white, Duftite leaves pale green to white; luster reads silky to subadamantine on Nickelaustinite and dull to vitreous on fractures on Duftite.
Often found alongside nickelaustinite
Minerals reported to co-occur with nickelaustinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaNiAsO₄(OH)
- Mohs hardness
- 4
- Density
- 4.3 g/cm³
- Colors
- Streak
- White
- Luster
- Silky to subadamantine
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Crusts, botryoidal, acicular crystals
- Cleavage
- On {110}, good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- On dolomite
Where rockhounds find nickelaustinite
Classic worldwide localities
- Bou Azzer, Anti-Atlas Mountains, Morocco
Field-hunting tip
Where it forms: On dolomite. If you start seeing roselite, calcite, dolomite in float, you are in the right ground. Typical habit: crusts, botryoidal, acicular crystals. Train your eye for that shape before scanning the outcrop.
Common questions
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Find nickelaustinite on the map
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