Lonecreekite is an extremely rare ammonium iron sulfate mineral that forms as small, colorless octahedrons. It is typically found as a secondary mineral in shale, resulting from the weathering of iron-rich sulfides, and is highly soluble in water, requiring dry storage for preservation.
Is this lonecreekite?
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 lonecreekite with a known reference. Lonecreekite sits at Mohs 2-3, 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: vitreous.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: cubic. Typical habit: octahedral crystals.
Often confused with
Lonecreekite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside lonecreekite
Minerals reported to co-occur with lonecreekite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (NH₄)Fe(SO₄)₂·12H₂O
- Mohs hardness
- 2-3
- Density
- 1.693 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Cubic
- Crystal habit
- Octahedral crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral probably formed by alteration of pyrite and reaction, at pH < 1, with ammonia fumes produced as the result of decay of organic matter (Hyrax excreta)
Where rockhounds find lonecreekite
Classic worldwide localities
- Lone Creek Fall cave, near Sabie, eastern Transvaal, South Africa (type locality)
Field-hunting tip
Where it forms: A rare secondary mineral probably formed by alteration of pyrite and reaction, at pH < 1, with ammonia fumes produced as the result of decay of organic matter (Hyrax excreta). If you start seeing clairite, sabieite, tschermigite in float, you are in the right ground. Typical habit: octahedral crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify lonecreekite?+
Where is lonecreekite found?+
What rocks look like lonecreekite?+
What minerals are found with lonecreekite?+
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Find lonecreekite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
