Ludlamite
Ludlamite is a hydrated iron phosphate, Fe3(PO4)2·4H2O: monoclinic, apple-green, hardness 3.5, density 3.12 to 3.19, named for Henry Ludlam. Vivianite compared.
Ludlamite is a hydrated iron phosphate, Fe3(PO4)2·4H2O: monoclinic, apple-green to bright green, hardness 3.5, density 3.12 to 3.19, with one perfect cleavage. It forms in complex granite pegmatites from earlier phosphates. The IMA list gives 1885 and the United Kingdom; it honours the London collector Henry Ludlam. Vivianite has twice its water molecules.
In short
- The identity card, from the Handbook of Mineralogy sheet: monoclinic, apple-green to bright green, streak pale greenish white, hardness 3.5, measured density 3.12 to 3.19, perfect {001} cleavage with a pearly lustre on it. Crystals are usually tabular, to 9 cm.
- Two formulas. The Handbook writes (Fe2+,Mg,Mn2+)3(PO4)2·4H2O; the September 2026 IMA-CNMNC Master List writes Fe2+3(PO4)2(H2O)4, status G, 1885, United Kingdom. Worked, the iron end is 50.18% FeO, 33.05% P2O5 and 16.78% water, the sheet’s ideal column to within 0.01.
- The water ladder. Phosphoferrite, ludlamite and vivianite are all Fe2+3(PO4)2 on the IMA list, with 3, 4 and 8 waters. Worked, that is 13.13%, 16.78% and 28.73% water by mass. Density falls as water rises: 3.10 to 3.29, 3.12 to 3.19, then 2.68.
- The scale separates vivianite, not phosphoferrite. A 20.00 g piece weighs 13.59 to 13.73 g in water as ludlamite and 12.54 g as vivianite. Phosphoferrite, 13.55 to 13.92 g, overlaps ludlamite completely; hardness, 4 to 4.5 against 3.5, and the crystal system separate them.
- Wheal Jane comes first on the sheet, not as a type locality. The Distribution field opens with Wheal Jane, Kea, Cornwall, and the X-ray pattern is from Wheal Jane. Neither the sheet nor the IMA list names a type locality, so this page does not call it one.
| Species | IMA formula | IMA status, year, country | Crystal system | Water by mass (worked) | Hardness | Density (measured) | Colour | Streak | 20.00 g piece in water |
|---|---|---|---|---|---|---|---|---|---|
| Phosphoferrite | Fe2+3(PO4)2(H2O)3 | Rd; 1980 s.p.; Germany | Orthorhombic | 13.13% | 4 to 4.5 | 3.10 to 3.29 | Pale green, olive-green, brownish green; reddish brown if oxidized | Not printed | 13.55 to 13.92 g |
| Ludlamite | Fe2+3(PO4)2(H2O)4 | G; 1885; United Kingdom | Monoclinic | 16.78% | 3.5 | 3.12 to 3.19 | Apple-green to bright green | Pale greenish white | 13.59 to 13.73 g |
| Vivianite | Fe2+3(PO4)2(H2O)8 | G; 1817; United Kingdom | Monoclinic | 28.73% | 1.5 to 2 | 2.68 | Colourless, very pale green, with oxidation dark blue, indigo-blue, then black | White, altering to dark blue, brown | 12.54 g |
What is ludlamite? An iron phosphate with four waters
The formula, both ways. The Handbook of Mineralogy sheet heads it (Fe2+,Mg,Mn2+)3(PO4)2·4H2O, allowing magnesium and manganese at the iron site. The September 2026 IMA-CNMNC Master List writes Fe2+3(PO4)2(H2O)4, iron alone, status G, 1885, United Kingdom, first reference Mineralogical Magazine 6 (1885), 23.
Worked on standard atomic weights, Fe3(PO4)2·4H2O has a formula mass of 429.53: 50.18% FeO, 33.05% P2O5, 16.78% H2O, or 39.00% iron as the element. The sheet’s ideal column prints 50.18, 33.04 and 16.78. Its one analysis, from the Palermo #1 mine, New Hampshire, gives FeO 49.22 and MgO 0.96. Divided by their formula masses, iron is 96.6% of those two cations and magnesium 3.4%, consistent with the IMA’s iron-only formula.
The name is to honor Henry Ludlam (1824–1880), English mineral collector, London, England, and the type material is in the Natural History Museum, London, number 44187. The sheet’s forms are {100}, {110}, {001} and {-111}; pdftotext dropped the bar on the last, and we read it from the rendered sheet.
Ludlamite, phosphoferrite and vivianite: the water ladder
Three species, one iron phosphate, different water. Method: we read the IMA rows of the three Fe2+3(PO4)2 hydrates on the September 2026 list and worked each from standard atomic weights. Phosphoferrite has 3 waters, 13.13% by mass; ludlamite 4, 16.78%; vivianite 8, 28.73%. Vivianite carries 1.71 times ludlamite’s water fraction.
What changes with the water. Density falls from ludlamite’s 3.12 to 3.19 to vivianite’s 2.68, and hardness from 3.5 to 1.5 to 2. Phosphoferrite, with the least water, is the hardest of the three at 4 to 4.5; its measured density, 3.10 to 3.29, brackets ludlamite’s. The vivianite sheet records it colorless, very pale green, with oxidation becoming dark blue. The ludlamite sheet records apple-green to bright green and no colour change; this page adds none. Vivianite’s change is on is vivianite light sensitive.
The scale, worked. A 20.00 g piece weighs 13.59 to 13.73 g in water as ludlamite and 12.54 g as vivianite, at least 1.05 g apart. Phosphoferrite gives 13.55 to 13.92 g, which overlaps ludlamite completely: that pair needs hardness or the crystal system. The side-by-side identification is on ludlamite vs vivianite; the method on how to measure specific gravity at home.
How ludlamite forms: pegmatite phosphates under reducing conditions
The Occurrence field reads in complex granite pegmatites, a common hydrothermal alteration product of earlier phosphates, formed under reducing conditions. Both formulas write the iron as ferrous, Fe2+.
Its company, by locality. At Hagendorf, Bavaria, the sheet lists phosphoferrite, triploidite, triplite, triphylite and apatite. At the Palermo #1 mine, New Hampshire, it lists fairfieldite, vivianite, siderite and whitlockite. The phosphoferrite sheet gives that mineral as an alteration product of triphylite in zoned complex granite pegmatites, at Hagendorf and Palermo too.
The localities are not all called pegmatites. The Distribution field uses the word for the Keystone pegmatites in South Dakota and the Énio pegmatite mine in Brazil. For Wheal Jane, the Stari Trg mine, the Blackbird mine, Santa Eulalia and the Bolivian localities it gives mine or district names only. We do not classify their geology.
Where ludlamite is found: Cornwall, Bavaria, Bolivia and Brazil
The Distribution field opens Some localities for fine crystals or large masses include: from Wheal Jane, Kea, Cornwall, England. It continues with Hagendorf, Bavaria; the Stari Trg mine (Trepça); the Palermo #1 mine, New Hampshire; large crystals from the Blackbird mine, Idaho; the Dan Patch, Ferguson and Big Chief pegmatites near Keystone, South Dakota; the Rapid Creek district, Yukon; and large crystals from the San Antonio mine, Santa Eulalia, Chihuahua.
Brazil and Bolivia. It lists the Énio pegmatite mine, northeast of Galiléia, Minas Gerais, and fine crystals from Morococala and Huanuni, Oruro, Bolivia; also the Ashio mine, Japan.
Is Wheal Jane the type locality? Neither source says so. The IMA list gives the United Kingdom and 1885. The sheet lists Wheal Jane first among localities for fine crystals, takes its powder pattern from Wheal Jane, and prints no [TL] marker. This page does not call it the type locality; the term is explained on what is a type locality. See Cornwall for the county, and the rest of the reference section at the species index. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.