Amarantite is a rare hydrated iron sulfate typically found as a secondary mineral in the oxidized zones of iron-rich sulfide deposits. Collectors should look for its distinctive deep orange-red tabular crystals often forming subparallel, sheaf-like aggregates.
Is this amarantite?
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 amarantite with a known reference. Amarantite 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. Amarantite leaves a yellowish-orange streak.
- 3Read the lusterHold the specimen under a strong light. Amarantite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: orange, brownish-red.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular crystals, subparallel aggregates, drusy coatings.
Often confused with
Amarantite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Amarantite leaves yellowish-orange, Fibroferrite leaves white; luster reads vitreous on Amarantite and silky on Fibroferrite.
How to tell apart: Streak differs — Amarantite leaves yellowish-orange, Copiapite leaves yellow; luster reads vitreous on Amarantite and pearly on Copiapite.
How to tell apart: Streak differs — Amarantite leaves yellowish-orange, Metahohmannite leaves yellow.
Often found alongside amarantite
Minerals reported to co-occur with amarantite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe³⁺₂(SO₄)₂(OH)₂·7H₂O
- Mohs hardness
- 2.5
- Density
- 3.31 g/cm³
- Colors
- Streak
- Yellowish-orange
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Tabular Crystals, Subparallel Aggregates, Drusy Coatings
- Cleavage
- Good On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Sulfide Deposits
- Typical price
- $50-300 per thumbnail or small specimen
Where rockhounds find amarantite
Classic worldwide localities
- Chile (Cerro Pintados)
- Argentina (Capillitas Mine)
- USA (New Almaden district)
Field-hunting tip
Look in oxidized zones of sulfide deposits country — that is the host setting where amarantite typically forms. If you start seeing fibroferrite, copiapite, hohmannite in float, you are in the right ground. Field specimens usually show a tabular crystals, subparallel aggregates, drusy coatings habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find amarantite on the map
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