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, so 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, so 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, 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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