Waterhouseite is a very rare manganese phosphate mineral occurring as dark, tabular crystals in manganese-rich metamorphic environments. It is primarily sought by advanced mineral collectors specializing in phosphate species or manganese minerals, as it is found in very few locations worldwide.
Is this waterhouseite?
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 waterhouseite with a known reference. Waterhouseite sits at Mohs 4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellowish brown.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to pearly on cleavage surfaces.
- 4Match the color rangeCompare against the expected color range: resinous orange brown, dark clove brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals.
Often confused with
Waterhouseite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Hematite is the harder of the two (Mohs 5-6 vs. 4); streak differs, so Waterhouseite leaves yellowish brown, Hematite leaves cherry-red or reddish brown; luster reads vitreous to pearly on cleavage surfaces on Waterhouseite and metallic or submetallic to dull on Hematite.
How to tell apart: Ilmenite is the harder of the two (Mohs 5-6 vs. 4); streak differs, so Waterhouseite leaves yellowish brown, Ilmenite leaves black to reddish brown; luster reads vitreous to pearly on cleavage surfaces on Waterhouseite and metallic to submetallic on Ilmenite.
Often found alongside waterhouseite
Minerals reported to co-occur with waterhouseite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn₇(PO₄)₂(OH)₈
- Mohs hardness
- 4
- Density
- 3.55 g/cm³
- Colors
- Resinous orange brownDark clove brown
- Streak
- Yellowish brown
- Luster
- Vitreous to pearly on cleavage surfaces
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular crystals
- Cleavage
- Perfect on (100) and probable on (001)
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In cavities in the carbonate-rich beds of a Precambrian banded iron formation
Where rockhounds find waterhouseite
Classic worldwide localities
- Iron Monarch quarry, Iron Knob, South Australia (type locality)
Field-hunting tip
Where it forms: In cavities in the carbonate-rich beds of a Precambrian banded iron formation. If you start seeing shigaite, gatehouseite, seamanite in float, you are in the right ground. Typical habit: tabular crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify waterhouseite?+
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Find waterhouseite on the map
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