Hureaulite
Hureaulite, Mn2+5(PO3OH)2(PO4)2(H2O)4: monoclinic pink to orange pegmatite phosphate, hardness 3.5, density 3.15 to 3.19, 37.70% Mn. Analyses, localities.
Hureaulite is a hydrated manganese phosphate, Mn2+5(PO3OH)2(PO4)2(H2O)4 on the IMA list: monoclinic pink, orange to reddish brown prisms to 3 cm, hardness 3.5, density 3.15 to 3.19, streak nearly white. It is 37.70% manganese by mass and forms late, by alteration of primary phosphates in complex granite pegmatites, with lithiophilite, triphylite and strengite.
In short
- The formula, checked. The September 2026 IMA-CNMNC Master List writes Mn2+5(PO3OH)2(PO4)2(H2O)4, status Rn, 2007 s.p.; the Handbook of Mineralogy sheet writes the same atoms in another order. On standard atomic weights that is 728.65 g/mol and 37.70% manganese, and its oxide column, MnO 48.68, P2O5 38.96, H2O 12.36, is the sheet’s ideal column to the second decimal.
- The manganese-majority check. Recast to atoms per 4 phosphorus, the sheet’s Huréaux, France, analysis has 3.46 Mn and 1.15 Fe, and its São Jose de Safira, Brazil, microprobe analysis 3.02 Mn and 2.14 Fe. Iron reaches 25.0% and 41.5% of iron plus manganese, so manganese leads in both, as the name of the formula requires.
- One phosphate in seven. A script over the IMA list finds 7 rows written as five metals with (XO3OH)2(XO4)2(H2O)4. Hureaulite is the only one with phosphorus; the other six are arsenates, and miguelromeroite, Mn2+5(AsO3OH)2(AsO4)2(H2O)4, is its arsenic counterpart. No row in that pattern has iron as a metal.
- Where it grows. A late-stage secondary mineral formed by alteration of primary phosphates in complex granite pegmatites. Its associates include strengite, eosphorite, rockbridgeite, cacoxenite and vivianite. The beraunite sheet names huréaulite as an associate; the hureaulite sheet does not name beraunite.
| Row or analysis | Formula as printed | Status, year, country | X | Metals | Fe share of Fe + Mn |
|---|---|---|---|---|---|
| Hureaulite | Mn2+5(PO3OH)2(PO4)2(H2O)4 | Rn, 2007 s.p., France | P | Mn 5 | 0% |
| Huréaux, France (sheet analysis 1) | Analysis | — | P | Mn 3.46, Fe 1.15 (sum 4.61) | 25.0% |
| São Jose de Safira, Brazil (sheet analysis 2) | Microprobe, total Fe as FeO, H2O by difference | — | P | Mn 3.02, Fe 2.14, Mg + Ca 0.11 (sum 5.27) | 41.5% |
| Miguelromeroite | Mn2+5(AsO3OH)2(AsO4)2(H2O)4 | A, 2008-066, Mexico | As | Mn 5 | — |
| Villyaellenite | Mn3Ca2(AsO3OH)2(AsO4)2(H2O)4 | A, 1983-008a, France | As | Mn 3, Ca 2 | — |
| Giftgrubeite | CaMn2Ca2(AsO3OH)2(AsO4)2(H2O)4 | A, 2016-102, France | As | Ca 3, Mn 2 | — |
| Sainfeldite | Ca5(AsO3OH)2(AsO4)2(H2O)4 | A, 1963-018, France | As | Ca 5 | — |
| Chongite | Ca3Mg2(AsO3OH)2(AsO4)2(H2O)4 | A, 2015-039, Chile | As | Ca 3, Mg 2 | — |
| Nyholmite | Cd3Zn2(AsO3OH)2(AsO4)2(H2O)4 | A, 2008-047, Australia | As | Cd 3, Zn 2 | — |
What is hureaulite? A manganese phosphate from pegmatites
On the IMA list, Mn2+5(PO3OH)2(PO4)2(H2O)4, status Rn, 2007 s.p., country France. Rn means renamed during the IMA era. The Handbook of Mineralogy hureaulite sheet is headed Huréaulite, with an accent, and writes Mn2+5(PO4)2(PO3OH)2·4H2O. This page uses the IMA spelling. The sheet’s occurrence line reads a late-stage secondary mineral formed by alteration of primary phosphates in complex granite pegmatites.
On the sheet. Monoclinic, point group 2/m, space group C2/c (synthetic). Crystals long to short prismatic, elongated along [001], with {100}, {110}, or tabular {100}, to 3 cm, may be equant; in bundled fascicles, less commonly fibrous, scaly, compact, massive. Cleavage on {100}, good; hardness 3.5; density 3.15 to 3.19 measured, 3.19 calculated. Transparent to translucent; vitreous, inclined towards greasy; streak nearly white. Biaxial (−), with pleochroism X colourless, Y yellow to pale rose, Z reddish yellow to reddish brown, and very strong crossed dispersion.
Positive control. With the sheet’s cell, a = 17.587, b = 9.127, c = 9.497 Å, β = 96.68°, Z = 4, the IMA formula gives a calculated density of 3.197, against the printed 3.19. A 20.00 g piece therefore reads 13.65 to 13.73 g in water across the measured range; the method is on how to measure specific gravity at home.
How much iron can hureaulite carry? The manganese-majority check
Up to 41.5% of its iron plus manganese, on the sheet’s own analyses. The Huréaux, France, analysis (P2O5 38.00, FeO 11.10, MnO 32.85, H2O 18.00) recasts to 3.46 Mn and 1.15 Fe per 4 P. The São Jose de Safira, Brazil, analysis, an electron-microprobe average of three with total Fe as FeO and H2O by difference (P2O5 38.09, FeO 20.65, MnO 28.72, MgO 0.30, CaO 0.38), recasts to 3.02 Mn, 2.14 Fe and 0.11 Mg + Ca.
What that shows, and what it does not. Manganese is the larger of the two in both, which is what the IMA formula, written with Mn2+ alone, requires of a hureaulite. The Huréaux metals sum to 4.61 per 4 P rather than 5, and its 18.00% water is well above the ideal 12.36%; the sheet does not comment on either. An old wet analysis is a record, not a correction of the formula. The script finds no IMA row with iron in hureaulite’s formula pattern, so this page names no iron analogue.
What does hureaulite look like?
Pink to orange and brown prisms, often in bundles. The sheet’s colour list is light pink, rose-violet, pale rose, amber, orange, red-orange, red, brownish orange, and reddish to yellowish brown. Prismatic crystals reach 3 cm and grow in bundled fascicles. The nearly white streak and hardness 3.5 are the sheet’s other quick readings; the method is on how to test mineral hardness properly.
Its neighbours on the pegmatite shelf. The sheet’s associates are lithiophilite, triphylite, heterosite, rockbridgeite, cacoxenite, vivianite, fairfieldite, dickinsonite, eosphorite, stewartite, strengite, phosphosiderite, roscherite and many rarer phosphates. Pink strengite is on the list; its in-water weights and colours are set out on its own page. Other phosphates on this site include phosphophyllite and hopeite.
Where is hureaulite found? Huréaux, Hagendorf, Minas Gerais
Distribution, as printed. In France, Huréaux, St. Sylvestre, and the La Vilate quarry near Chanteloube, Haute-Vienne. The Mangualde pegmatite near Mesquitela, Portugal. In Germany, fine crystals from Hagendorf, and Pleystein and Hühnerkobel near Zwiesel, Bavaria. The Varuträsk pegmatite, Västerbotten, Sweden, and the Viitaniemi pegmatite near Eräjärvi, Finland.
The Americas, Africa and Asia. In the USA, the Strickland quarry, Portland, and Branchville, Connecticut; the Fletcher and Palermo #1 mines near North Groton, New Hampshire; the Emmons quarry, Greenwood, and many other places in Maine; the Bull Moose, Tip Top and White Elephant mines, Custer Co., South Dakota. In Brazil, the Sapucaia pegmatite mine, and fine examples from the Criminoso mine near São Jose de Safira and the Joca mine, Galiléia, Minas Gerais. The Buranga pegmatite near Gatumba, Rwanda; extraordinary crystals from Shengus, Gilgit district, Pakistan.
Type locality. The sheet marks none; it says the name is for the first-noted occurrence near Huréaux, and the IMA list gives France. See what is a type locality. More phosphates are at the species index. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.