Ludlamite is a highly sought-after secondary phosphate mineral known for its vibrant green, often translucent, tabular crystals. It typically occurs as well-defined, fan-shaped aggregates or intergrown crystals in phosphate-rich hydrothermal veins. Collectors prize specimens for their distinct color and geometric crystalline beauty.
Is this ludlamite?
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 ludlamite with a known reference. Ludlamite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ludlamite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Ludlamite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: light green, bottle green, dark green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, bladed, fan-shaped clusters.
Often confused with
Ludlamite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside ludlamite
Minerals reported to co-occur with ludlamite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe₂²⁺Fe²⁺(PO₄)₂·4H₂O
- Mohs hardness
- 3.5
- Density
- 3.12 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Bladed, Fan-shaped Clusters
- Cleavage
- Perfect On {010}
- Rarity
- Rare
- Uses
- Collector, Specimen
- Host rock
- Hydrothermal Phosphate-rich Mineral Deposits
- Typical price
- $50-500 depending on crystal size and quality
Where rockhounds find ludlamite
Classic worldwide localities
- Llallagua, Bolivia
- Hagendorf, Germany
- Cornwall, England
- Blackbird Mine, Idaho, USA
Field-hunting tip
Look in hydrothermal phosphate-rich mineral deposits country — that is the host setting where ludlamite typically forms. If you start seeing vivianite, siderite, apatite in float, you are in the right ground. Field specimens usually show a tabular crystals, bladed, fan-shaped clusters habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find ludlamite on the map
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