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?
4-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 3-3.5, softer than the next harder reference, harder than the previous one.
- 2Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 3Match the color rangeCompare against the expected color range: black.
- 4Look 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.
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
- 3-3.5
- Density
- 2.529 g/cm³
- Colors
- Luster
- Vitreous
- Transparency
- Opaque to translucent on thin edges
- Crystal system
- Cubic
- Crystal habit
- Octahedral crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As efflorescence that covers walls in cracks around gas/steam (∼100°C.) vents in strongly hydrothermally-altered andesite-basalt in a geothermal region characterized by a high ammonium concentration
Where rockhounds find ammoniovoltaite
Classic worldwide localities
- North Kambalny geothermal field, Kambalny volcanic ridge, Kamchatka, Russia
Field-hunting tip
Where it forms: As efflorescence that covers walls in cracks around gas/steam (∼100°C.) vents in strongly hydrothermally-altered andesite-basalt in a geothermal region characterized by a high ammonium concentration. If you start seeing alunogen, tschermigite, pyrite in float, you are in the right ground. Typical habit: octahedral crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ammoniovoltaite?+
Where is ammoniovoltaite found?+
What rocks look like ammoniovoltaite?+
What minerals are found with ammoniovoltaite?+
What kind of rock does ammoniovoltaite form in?+
What is ammoniovoltaite used for?+
Find ammoniovoltaite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
