Variscite
Variscite is Al(PO4)(H2O)2: orthorhombic, hardness 4.5, density 2.57 to 2.61, green and massive. No copper; its indices end at 1.594, turquoise's begin at 1.61.
Variscite is a hydrated aluminium phosphate, Al(PO4)(H2O)2 on the IMA list: orthorhombic, hardness 4.5, density 2.57 to 2.61, usually green and massive in nodules and veinlets. It carries no copper, unlike turquoise, and its refractive indices top out at 1.594 where turquoise starts at 1.61. Strengite is its iron analogue; metavariscite its dimorph.
In short
- One species, a series and a dimorph. The September 2026 IMA-CNMNC Master List lists variscite as Al(PO4)(H2O)2, status A, 1967 s.p., Germany; strengite, Fe3+(PO4)(H2O)2, status G, 1877, Germany; and metavariscite with the same formula as variscite, status A, 1967 s.p., USA. A script finds 10 rows with the formula shape M3+(XO4)(H2O)2, phosphates and arsenates alike.
- The 1.6 gap. The Handbook of Mineralogy sheets give variscite α 1.550 to γ 1.594 and turquoise α 1.61, β 1.62, γ 1.65. Nothing on the variscite sheet reaches 1.60. A refractometer reading at or above 1.61 is not variscite; below 1.60 is not turquoise.
- Where the gap fails. The International Gem Society says common turquoise treatments may mask turquoise’s higher indices, and that variscite misrepresented as turquoise may be dyed, waxed or polymer-impregnated. A treated cabochon can read on the wrong side, so the gap rules out; it does not prove.
- Weighing helps less than it looks. A 20.00 g piece reads 12.22 to 12.34 g in water as variscite and 13.01 g as turquoise at its sheet density, a 0.67 g gap. But the turquoise sheet says less if massive, and GIA gives turquoise 2.76 (+0.14, −0.36): 11.67 to 13.10 g, which covers variscite.
- Cornwall is on the sheet. The Distribution field names the Gunheath and Hensbarrow china clay pits, St Austell, and the Treore mine, St Teath, Cornwall, beside the Utah nodules of Clay Canyon and Lucin, the Cole mine at Bisbee, and Messbach in Saxony.
| Species (IMA formula) | Crystal system | Hardness | Density, measured | Refractive indices | Streak; colour on the sheet | 20.00 g piece in water |
|---|---|---|---|---|---|---|
| Variscite, Al(PO4)(H2O)2 | Orthorhombic | 4.5 | 2.57 to 2.61 | α 1.550 to 1.563; γ 1.570 to 1.594 | White; pale green, emerald-green, bluish green, colourless, rarely red | 12.22 to 12.34 g |
| Metavariscite, Al(PO4)(H2O)2 | Monoclinic | 3.5 | 2.51 to 2.54 | α 1.551; β 1.558; γ 1.582 | White; pale green | 12.03 to 12.13 g |
| Strengite, Fe3+(PO4)(H2O)2 | Orthorhombic | 3.5 | 2.84 to 2.87 | α 1.697 to 1.708; γ 1.741 to 1.745 | White; purple, violet, pink, carmine, greenish white | 12.96 to 13.03 g |
| Turquoise, CuAl6(PO4)4(OH)8(H2O)4 (sheet) | Triclinic | 5 to 6 | 2.86, less if massive | α 1.61; β 1.62; γ 1.65 | White to pale greenish blue; sky-blue, bluish green, apple-green, greenish grey | 13.01 g |
| Turquoise (GIA) | 5 to 6 | 2.76 (+0.14, −0.36) | 1.610 to 1.650 | 11.67 to 13.10 g | ||
| Variscite against turquoise (sheets) | Different systems | Variscite softer by 0.5 to 1.5 | Variscite lower by 0.25 to 0.29 | Gap of 0.016 | Turquoise streak can be tinted; variscite’s is white | 0.67 to 0.79 g lighter; overlaps GIA’s turquoise range |
What is variscite? An aluminium phosphate with no copper
The names. The September 2026 IMA-CNMNC Master List gives variscite as Al(PO4)(H2O)2, status A, 1967 s.p., country Germany, with a first reference to the Journal für Praktische Chemie, volume 10 (1837), page 506. The Handbook sheet writes AlPO4·2H2O, the group line Variscite group, and the Name field from Variscia, an old name for Vogtland, the district in Germany which was the original source for the mineral.
What it looks like, per the sheet. Orthorhombic; uncommon as crystals, which are pseudo-octahedral {111}, may be lathlike, and reach only 1.5 mm. Usually fine-grained massive, in nodules, stalactites, crusts and veinlets. Pale green, emerald-green or bluish green, also colourless, pale brown or yellow, rarely red. White streak; vitreous to waxy lustre. Hardness 4.5; density 2.57 to 2.61. Good cleavage on {010}, poor on {001}.
By mass. On standard atomic weights, Al(PO4)(H2O)2 is 17.08% aluminium, 19.61% phosphorus and 22.81% water. As oxides that is Al2O3 32.27, P2O5 44.92 and H2O 22.81, the ideal column the sheet prints. The sheet records no luminescence, by a ligature-aware search.
Is it variscite or turquoise? The 1.6 gap, and where it fails
The 1.6 gap: no index on the variscite sheet reaches 1.60, and none on the turquoise sheet falls below 1.61. Variscite prints α 1.550 to 1.563, β 1.565 to 1.588 and γ 1.570 to 1.594; turquoise prints 1.61, 1.62 and 1.65; GIA gives turquoise 1.610 to 1.650. The International Gem Society gives a variscite shadow edge at about 1.56.
The documented failures. The International Gem Society variscite article says even experts may find the two hard to separate, that common turquoise treatments may mask turquoise’s higher indices, and that variscite passed off as turquoise may be dyed or wax- or polymer-impregnated. It adds that variscite generally looks greener, which it calls hardly diagnostic. Hardness, 4.5 against 5 to 6, is a destructive test on a finished stone; see how to test mineral hardness properly.
The scale. At the sheet densities, a 20.00 g piece reads 12.22 to 12.34 g in water as variscite and 13.01 g as turquoise. The turquoise sheet qualifies its 2.86 with less if massive, and GIA’s turquoise range, 2.76 with +0.14 and −0.36, runs from 2.40 to 2.90, covering variscite. Both are porous when massive, and porous pieces take up water during weighing; see how to measure specific gravity at home. The howlite and magnesite tests for turquoise are on how to tell real turquoise from fake and are not repeated here.
Variscite, strengite and metavariscite: one formula shape, three species
The series. The variscite sheet says variscite forms a series with strengite, and the strengite sheet says the same in reverse. Strengite is Fe3+(PO4)(H2O)2: iron in the place of aluminium, 29.89% iron by mass. Its sheet gives hardness 3.5, density 2.84 to 2.87 and colours of purple, violet, pink, peach-blossom-red and carmine, with indices from α 1.697 to γ 1.745.
The Lucin check. The sheet’s analysis from Lucin, Utah reads P2O5 44.73, Al2O3 32.40, H2O 22.68, V2O5 0.32, Cr2O3 0.18 and Fe2O3 0.06. Worked on standard atomic weights, aluminium is 99.51% of the trivalent site, chromium 0.37% and iron 0.12%, and phosphorus plus vanadium balance the site at 0.992. The Lucin material sits at the aluminium end of the series; the strengite component is about one part in 800.
The dimorph and the shape count. Metavariscite has variscite’s formula but is monoclinic, with hardness 3.5 and density 2.51 to 2.54 on its sheet. A script over the 2026 IMA list finds 10 rows of the shape M3+(XO4)(H2O)2: bonacinaite, kolbeckite, mansfieldite, metavariscite, parascorodite, phosphosiderite, scorodite, strengite, variscite and yanomamite. That is a count of formulas, not of the variscite group, which the list does not print.
Where variscite is found: Utah, Nevada, Cornwall and Saxony
The Occurrence field: typically deposited from phosphate-bearing waters in contact with aluminous rocks; on islands and in caves the phosphate comes from decomposing guano. At the Little Green Monster mine, Utah, the associates are crandallite, carbonate-fluorapatite, wardite, millisite, gordonite, montgomeryite, overite, kolbeckite and goyazite.
The Distribution field opens many localities and names: Messbach near Oelsnitz, Langenstriegis and Lichtenberg, Germany; the Drachenhöhle, Austria; Palazuelo de las Arribas, Spain; the Gunheath and Hensbarrow china clay pits, St Austell, and the Treore mine, St Teath, Cornwall; Sarysai, Kazakhstan; in Utah, large nodules from the Little Green Monster mine, Clay Canyon, near Fairfield, from Utahlite Hill near Lucin and from Amatrice Hill, Tooele County; the Henry de Linde mine and Dug Hill, Arkansas; the Cole mine, Bisbee; crystals in the Goldstrike, Genesis and Gold Quarry mines, Nevada; the Sapucaia pegmatite, Minas Gerais; and sites in South Africa, Kenya, Australia and Japan.
Trade names. The International Gem Society says Utah variscite is sometimes called lucinite or utahlite, variscite mixed with quartz from Ely, Nevada amatrice or amatrix, and banded variscite sabalite. None has an IMA row, by script. The reference section is at the species index. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.