Augelite
Augelite, Al2(PO4)(OH)3: a colourless to pale rose aluminium phosphate, monoclinic, hardness 4.5 to 5, density 2.696, perfect {110} cleavage, pearly lustre.
Augelite is a basic aluminium phosphate, Al2(PO4)(OH)3 on the IMA list (G, 1868, Sweden): monoclinic, colourless to white, yellowish, pale rose or greenish, hardness 4.5 to 5, density 2.696, with a perfect {110} cleavage that gives the pearly lustre its Greek name refers to. Its Handbook sheet names Sweden, Uganda, Rwanda, the USA, Canada, Bolivia and Australia, not Peru.
In short
- Formula and name. The September 2026 IMA-CNMNC Master List gives Al2(PO4)(OH)3, status G, 1868, Sweden, and the Handbook of Mineralogy sheet writes the same. Worked on standard atomic weights it is 26.99% aluminium and 15.49% phosphorus, with ideal oxides Al2O3 50.99, P2O5 35.49 and H2O 13.51, the sheet’s column (3) to within 0.01. The name is from the Greek for lustre, for the pearly lustre on its cleavage.
- The two-to-one check. Two aluminium to one phosphorus is the formula. The sheet’s analysis (2), Mt Perry, Queensland, by electron microprobe, gives Al:P = 2.020; shared over three cations that is Al 2.007 and P 0.993, the printed Al2.01(PO4)0.99. Analysis (1), the Västanå mine, Sweden, after deduction of quartz, gives 1.953, or 1.975 if its ferric iron is counted with aluminium.
- The 2.70 cell check. The cell, a 13.124, b 7.988, c 5.066 Å, β 112.25°, Z = 4, has a volume of 491.55 ų. Four formula units of 199.96 in it give 2.702, 0.002 under the printed 2.704 and 0.006 over the measured 2.696. A 20.00 g piece reads 12.58 g in water at 2.696, the figure on the brazilianite page.
- Gemstone? On one source, cut but not worn. The sheet prints no gem use. The International Gem Society augelite article describes faceted augelite, says most faceted stones from the California material weigh less than one carat, some up to three, and calls it difficult to cut. That is the source’s statement, attributed; this page gives no value or buying advice.
- Peru is not on the sheet. The Distribution field names the Västanå mine and Hålsjöberg, Sweden; Mbale, Uganda; the Buranga pegmatite, Rwanda; the Champion mine, California, for large crystals; New Hampshire, South Dakota and Arizona; the Big Fish River–Rapid Creek area, Yukon; the Oruro and Potosí districts of Bolivia; and Mt Perry, Queensland, and adds that further localities are known. It names no Peruvian locality, so neither does this page.
| Line | Worked from the sheet’s numbers | Printed on the sheet | Agrees? |
|---|---|---|---|
| Ideal Al2(PO4)(OH)3: Al per P | 2.000 | Column (3): Al2O3 50.99, P2O5 35.50, H2O 13.51 | Yes (worked 50.99, 35.49, 13.51) |
| Mt Perry, Queensland (2), microprobe, partial: Al per P | 2.020; Al 2.007, P 0.993 on three cations | Al2.01(PO4)0.99(OH)3 | Yes |
| Västanå mine, Sweden (1), after deduction of quartz: Al per P | 1.953; (Al + Fe3+) per P 1.975 | No formula printed | Below 2 by 0.025 to 0.047 |
| Västanå: water per P | 1.445 | Ideal 1.5 (three OH) | Close |
| Västanå: Ca and Mn per P | 0.039 and 0.009 | CaO 1.09, MnO 0.31 printed | Not in the formula |
| Density from the cell (491.55 ų, Z = 4) | 2.702 | D(calc.) 2.704; D(meas.) 2.696 | Yes, within 0.006 |
| 20.00 g piece in water | 12.58 g at 2.696; 12.60 g at 2.704 | — | — |
| Quartz, for comparison (quartz sheet) | 12.45 g at 2.65 | H 7; uniaxial (+), ω 1.544, ε 1.553; cleavage rarely observable | Separates on hardness, index and cleavage, barely on weight |
What is augelite? An aluminium phosphate with two aluminium per phosphorus
The formula. The September 2026 IMA list gives Al2(PO4)(OH)3, status G, 1868, Sweden, with a first reference in the Öfversigt af Kongliga Vetenskaps-Akademiens Förhandlingar for 1868 and a second in Zeitschrift für Kristallographie – Crystalline Materials 229 (2014). The Handbook of Mineralogy augelite sheet writes the same. Formula mass 199.96: 26.99% aluminium, 15.49% phosphorus. The sheet’s Name field: from the Greek for luster, for its pearly luster on the cleavage. Type material is given as n.d., not determined.
What the sheet describes. Monoclinic, C2/m; thick tabular crystals on {001} to 13 cm, which may be prismatic or even acicular along [001], with {110} striated; may be massive. Cleavage {110} perfect, {-201} good, {001} and {-101} imperfect (overbars read from the rendered sheet); fracture uneven; brittle; hardness 4.5 to 5. Colourless to white, may be yellowish to pale rose or greenish; white streak; vitreous, pearly on {110}. Biaxial (+), α 1.5736, β 1.5759, γ 1.5877. Method for the cleavage on cleavage or fracture: how to tell.
The two-to-one check, worked
Method. Each printed oxide weight is divided by its molar mass on standard atomic weights and the cations compared. The sheet’s analysis (2), from Mt Perry, 75 km southwest of Bundaberg, Queensland, is a partial electron-microprobe analysis: P2O5 34.68, SiO2 0.07, TiO2 0.08, Al2O3 50.33, with no water reported. Its Al:P is 2.020; shared over the three cations of the formula that is Al 2.007 and P 0.993, which round to the printed Al2.01(PO4)0.99(OH)3.
Documented failure: the Swedish analysis. Analysis (1), Västanå mine, printed after deduction of quartz impurity, reads P2O5 35.04, Al2O3 49.15, Fe2O3 0.89, MnO 0.31, CaO 1.09, H2O 12.85, total 99.33. Its Al:P is 1.953, and 1.975 with ferric iron counted as aluminium: short of 2 either way. It also carries 0.039 calcium and 0.009 manganese per phosphorus, which the formula has no place for. The sheet prints no formula for this analysis and does not say what the calcium is in; this page does not guess. Water comes out at 1.445 H2O per phosphorus against the formula’s 1.5.
Is augelite a gemstone?
The sheet says nothing about gems. It describes crystals to 13 cm and calls the large crystals from the Champion mine, White Mountains, Mono Co., California, out by name. The International Gem Society augelite article, by Joel E. Arem, describes faceted augelite, with most faceted gems from the California material under one carat and some up to three carats, and says it is difficult to cut; it gives hardness 4.5 to 5 and specific gravity 2.696 to 2.75, which at 2.75 is 12.73 g in water for 20.00 g. This page reports those statements as the gem society’s and gives no buying or wearing advice.
Fluorescence. The augelite sheet records no luminescence by a ligature-aware search. The gem society gives usually none, and reports a light yellow shortwave response from one find and none from other sources. UV exposure limits are in the ICNIRP 2004 guidelines on limits of exposure to ultraviolet radiation; this page is not safety advice. Background on fluorescent minerals explained.
Augelite or quartz? Colourless crystals compared
Three tests that separate them. The gem society’s photograph shows an augelite crystal on quartz, and both can be colourless. The quartz sheet gives hardness 7, against augelite’s 4.5 to 5; quartz is uniaxial (+) with ω 1.544 and ε 1.553, against augelite’s biaxial α 1.5736 to γ 1.5877, a gap of 0.0206 between quartz’s top and augelite’s bottom; and quartz cleavage is rarely observable, where augelite has a perfect {110} cleavage with a pearly lustre on it. Hardness method on how to test mineral hardness properly.
Documented failure: the balance. A 20.00 g piece reads 12.58 g in water as augelite and 12.45 g as quartz, 0.13 g apart; matrix quartz on an augelite crystal pulls the reading towards quartz. Weighing confirms; it does not decide. The method is on how to measure specific gravity at home.
Where is augelite found?
As the sheet prints it. From the Västanå mine, near Näsum, Skåne, and at Hålsjöberg, Värmland, Sweden. At Mbale, Uganda. In the Buranga pegmatite, near Gatumba, Rwanda. In the USA, large crystals from the Champion mine, White Mountains, Mono Co., California; in New Hampshire, at the Palermo #1 mine, near North Groton, Grafton Co., and the G.E. Smith mine, Newport, Sullivan Co.; in the Hugo and Ingersoll mines, near Keystone, Pennington Co., South Dakota; in the White Picacho district, Maricopa and Yavapai Cos., Arizona. From the Big Fish River–Rapid Creek area, Yukon Territory, Canada. In Bolivia, from the Socavón mine, San José, and Itos mines, Oruro; at Llallagua, Machacamarca, Tatasi and Portugalete, Potosí. From Mt Perry, Queensland. Additional localities are known. No type locality is marked; see what is a type locality.
Three settings. The sheet’s Occurrence field: formed by hydrogen metamorphism of phosphate-bearing rocks in peraluminous sediments, and in some high-temperature hydrothermal ore deposits. Associates: attakolite, svanbergite, lazulite, hematite, trolleite and berlinite at Västanå; lazulite, rutile, pyrophyllite and baryte at the Champion mine; arsenopyrite, stannite, pyrite, andorite, cassiterite and zinkenite in Bolivia. The brazilianite sheet lists augelite at Buranga too. More phosphates in the species index. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.