Hisingerite is an amorphous, iron-rich silicate mineral that commonly occurs as a secondary alteration product in igneous rocks or sulfide veins. It is typically found in massive, resinous, dark brown to black crusts that can be easily mistaken for other iron-rich amorphous minerals like allophane or limonite.
Is this hisingerite?
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 hisingerite with a known reference. Hisingerite 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. Hisingerite leaves a brown streak.
- 3Read the lusterHold the specimen under a strong light. Hisingerite typically shows a resinous luster.
- 4Match the color rangeCompare against the expected color range: black, brown, greenish-black.
- 5Look at form & habitCrystal system: amorphous. Typical habit: massive, reniform, or earthy crusts.
Often confused with
Hisingerite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Hisingerite leaves brown, Allophane leaves white; luster reads resinous on Hisingerite and vitreous on Allophane.
How to tell apart: Limonite is the harder of the two (Mohs 4-5.5 vs. 3); streak differs — Hisingerite leaves brown, Limonite leaves yellowish-brown; luster reads resinous on Hisingerite and submetallic to earthy on Limonite.
Often found alongside hisingerite
Minerals reported to co-occur with hisingerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe³⁺₂Si₂O₅(OH)₄·2H₂O
- Mohs hardness
- 3
- Density
- 2.2-2.5 g/cm³
- Colors
- Streak
- Brown
- Luster
- Resinous
- Transparency
- Opaque
- Crystal system
- Amorphous
- Crystal habit
- Massive, Reniform, Or Earthy Crusts
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Collector, Scientific Research
- Host rock
- Hydrothermal Veins and Igneous Weathering Zones
- Typical price
- $10-60 thumbnail
Where rockhounds find hisingerite
Classic worldwide localities
- Sweden
- Finland
- USA
- Germany
Field-hunting tip
Look in hydrothermal veins and igneous weathering zones country — that is the host setting where hisingerite typically forms. If you start seeing magnetite, quartz, pyrite in float, you are in the right ground. Field specimens usually show a massive, reniform, or earthy crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find hisingerite on the map
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