Matulaite is a rare phosphate mineral that typically forms as botryoidal or crust-like coatings in phosphate-rich localities. It is frequently associated with other secondary phosphate minerals like variscite and wavellite, often requiring magnification for accurate identification due to its small size.
Is this matulaite?
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 matulaite with a known reference. Matulaite sits at Mohs 1.5, 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: white, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: botryoidal, crusts, radial aggregates.
Often confused with
Matulaite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Wavellite is the harder of the two (Mohs 3.5-4 vs. 1.5).
How to tell apart: Variscite is the harder of the two (Mohs 4.5 vs. 1.5).
How to tell apart: Crandallite is the harder of the two (Mohs 5 vs. 1.5).
Often found alongside matulaite
Minerals reported to co-occur with matulaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- FeAl₇(PO₄)₄(PO₃OH)₂(OH)₈(H₂O)₈·8H₂O
- Mohs hardness
- 1.5
- Density
- 2.27 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Botryoidal, crusts, radial aggregates
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An uncommon secondary mineral in the oxidized zone of phosphatic iron deposits
Where rockhounds find matulaite
Classic worldwide localities
- Bachman iron mine, Hellertown, Northampton Co., and at General Trimble’s mine, Chester Co., Pennsylvania, USA
- LCA pegmatite, Bessemer City, Gaston Co., North Carolina, USA
- Candelaria mine, Candelaria district, Mineral Co., Nevada, USA
- Rotläufchen iron mine, Waldgirmes, near Wetzlar, Hesse, and at Hagendorf, Bavaria, Germany
- Fumade, Tarn, France
Field-hunting tip
Where it forms: An uncommon secondary mineral in the oxidized zone of phosphatic iron deposits. If you start seeing beraunite, rockbridgeite, dufrénite in float, you are in the right ground. Typical habit: botryoidal, crusts, radial aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify matulaite?+
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What rocks look like matulaite?+
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Find matulaite on the map
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