Metavoltine is a rare sulfate mineral that forms as a secondary alteration product in the oxidation zones of sulfide ore deposits. It is most easily identified by its characteristic hexagonal, micaceous plate habit and distinct yellow-orange coloration. Due to its solubility, it is best found in extremely arid environments where it can persist as thin crusts or small crystalline aggregates.
Is this metavoltine?
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 metavoltine with a known reference. Metavoltine sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brownish yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous.
- 4Match the color rangeCompare against the expected color range: greenish brown, yellow brown, orange brown, lemon.
- 5Look at form & habitCrystal system: trigonal. Typical habit: scaly, tabular.
Often confused with
Metavoltine vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Metavoltine leaves brownish yellow, Copiapite leaves pale yellow; luster reads resinous on Metavoltine and pearly on {010} on Copiapite.
How to tell apart: Streak differs, so Metavoltine leaves brownish yellow, Coquimbite leaves white; luster reads resinous on Metavoltine and vitreous on Coquimbite.
How to tell apart: Streak differs, so Metavoltine leaves brownish yellow, Jarosite leaves pale yellow; luster reads resinous on Metavoltine and subadamantine to vitreous, resinous on fractures on Jarosite.
Often found alongside metavoltine
Minerals reported to co-occur with metavoltine. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₂Na₆FeFe₆O₂(SO₄)₁₂·18H₂O
- Mohs hardness
- 2.5
- Density
- 2.51 g/cm³
- Streak
- Brownish yellow
- Luster
- Resinous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Scaly, tabular
- Cleavage
- Perfect on {0001}
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Typically an alteration product of pyrite in arid climates; formed as a fumarolic sublimate and solfataric precipitate; may be a post-mining product
Where rockhounds find metavoltine
Classic worldwide localities
- Sulfur Hole prospect, near Borate, about 10 km northeast of Yermo, Calico Hills, San Bernardino Co., California, USA
- Steamboat Hot Springs, Washoe Co., Nevada, USA
- Bisbee, Cochise Co., Arizona, USA
- Madeni Zakh, Iran
- Vesuvius, at the Grotta dello Zolfo, Miseno, and from Solfatara di Pozzuoli, Campi Flegrei, near Naples, Campania, Italy
- Cetine mine, 20 km southwest of Siena, Tuscany, Italy
Field-hunting tip
Where it forms: Typically an alteration product of pyrite in arid climates; formed as a fumarolic sublimate and solfataric precipitate; may be a post-mining product. If you start seeing voltaite, botryogen, ferrinatrite in float, you are in the right ground. Typical habit: scaly, tabular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify metavoltine?+
Where is metavoltine found?+
What rocks look like metavoltine?+
What minerals are found with metavoltine?+
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What is metavoltine used for?+
Find metavoltine on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
