Sabieite is an extremely rare ammonium iron sulfate mineral that typically forms as a white to yellowish efflorescence on coal seams undergoing combustion. Because it is highly soluble and unstable in humid conditions, it is rarely found in outdoor environments and must be stored in airtight, dry containers to prevent degradation.
Is this sabieite?
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 sabieite with a known reference. Sabieite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: earthy.
- 4Match the color rangeCompare against the expected color range: white.
- 5Look at form & habitCrystal system: trigonal. Typical habit: massive, powdery.
Often confused with
Sabieite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Alunite is the harder of the two (Mohs 3.5-4 vs. 2); luster reads earthy on Sabieite and vitreous, somewhat pearly on {0001} on Alunite.
How to tell apart: Streak differs, so Sabieite leaves white, Jarosite leaves pale yellow; luster reads earthy on Sabieite and subadamantine to vitreous, resinous on fractures on Jarosite.
Often found alongside sabieite
Minerals reported to co-occur with sabieite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (NH₄)Fe(SO₄)₂
- Mohs hardness
- 2
- Density
- 2.68-2.69 g/cm³
- Colors
- Streak
- White
- Luster
- Earthy
- Transparency
- Semitransparent
- Crystal system
- Trigonal
- Crystal habit
- Massive, powdery
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- Formed by dehydration of lonecreekite
Where rockhounds find sabieite
Classic worldwide localities
- Lone Creek cavern, near Sabie, Transvaal, South Africa (type locality)
Field-hunting tip
Where it forms: Formed by dehydration of lonecreekite. If you start seeing lonecreekite, tschermigite in float, you are in the right ground. Typical habit: massive, powdery. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify sabieite?+
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Find sabieite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
