Ammoniovoltaite is a rare sulfate mineral found primarily in fumarolic or post-mining environments where ammonium-rich solutions interact with iron-sulfide oxidation products. Collectors should look for dark, well-formed octahedral crystals typically found encrusting mine walls or localized in coal-bearing strata. It is highly soluble in water and should be kept in a dry, sealed environment to prevent degradation.
Is this ammoniovoltaite?
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 ammoniovoltaite with a known reference. Ammoniovoltaite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ammoniovoltaite leaves a greenish-white streak.
- 3Read the lusterHold the specimen under a strong light. Ammoniovoltaite typically shows a resinous luster.
- 4Match the color rangeCompare against the expected color range: black, dark green, brown.
- 5Look at form & habitCrystal system: cubic. Typical habit: octahedral crystals.
Often confused with
Ammoniovoltaite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Ammoniovoltaite leaves greenish-white, Voltaite leaves greenish gray.
How to tell apart: Ammoniovoltaite is noticeably harder (Mohs 3 vs. 1.5-2); streak differs, so Ammoniovoltaite leaves greenish-white, Pickeringite leaves white; luster reads resinous on Ammoniovoltaite and silky on Pickeringite.
Often found alongside ammoniovoltaite
Minerals reported to co-occur with ammoniovoltaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (NH₄)₂Fe₅Fe₃Al(SO₄)₁₂·18H₂O
- Mohs hardness
- 3
- Density
- 2.68 g/cm³
- Colors
- Streak
- Greenish-white
- Luster
- Resinous
- Transparency
- Translucent
- Crystal system
- Cubic
- Crystal habit
- Octahedral Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Post-mine Fumarole Deposits and Coal Fire Oxidation Zones
- Typical price
- $50-300 per specimen
Where rockhounds find ammoniovoltaite
Classic worldwide localities
- United Verde mine, Arizona, USA
- Alum Cave Bluff, Tennessee, USA
- Klodzko, Poland
Field-hunting tip
Look in post-mine fumarole deposits and coal fire oxidation zones country, the host setting where ammoniovoltaite typically forms. If you start seeing jarosite, gypsum, alunogen in float, you are in the right ground. Field specimens usually show a octahedral crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ammoniovoltaite?+
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How much is ammoniovoltaite worth?+
What rocks look like ammoniovoltaite?+
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Find ammoniovoltaite on the map
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