“Hureaulite,” Jocao Mine, Galileia, Doce valley, Minas Gerais, Brazil. © Rob Lavinsky, www.iRocks.com. Used with permission.
Hureaulite
Hureaulite can show rich and lively pink, rose, and orange colors. However, this collector’s gem is rarely cut.
Hureaulite Information
| Data | Value |
|---|---|
| Name | Hureaulite |
| Crystallography | Monoclinic. Crystals prismatic up to 3 cm, tabular; massive; compact. |
| Refractive Index | 1.637-1.663 |
| Colors | Pale rose, violet-rose, yellowish, red-orange, orange-red, brownish orange, yellowish to reddish brown, gray, colorless. |
| Luster | Vitreous to greasy. |
| Hardness | 3.5 |
| Fracture | Uneven |
| Specific Gravity | 3.19 |
| Birefringence | 0.012 |
| Cleavage | Good 1 direction |
| Luminescence | None. |
| Luminescence Present | No |
| Transparency | Transparent to translucent |
| Absorption Spectrum | Not diagnostic. |
| Formula | Mn5(PO4)2[(PO3)(OH)]2 · 4H2O. |
| Pleochroism | Colorless/pale rose to yellow/reddish yellow-brown. |
| Optics | a = 1.637-1.652; β = 1.645-1.658; γ = 1.649-1.663. Biaxial (-), 2V= 75°. |
| Optic Sign | Biaxial - |
| Etymology | After the type locality, Les Hureaux, France. |
| Occurrence | In phosphate masses in granite pegmatites. |
Hureaulite: Pala County, California (~3 inches across). Photo © Joel E. Arem, PhD, FGA. Used with permission.
Comments
With a hardness of 3.5, hureaulite is too soft for jewelry use. Massive material can yield cabochons, although these are seldom cut.
The hureaulite mineral group encompasses this manganese phosphate material as well as chongite, miguelromeroite, nyholmite, sainfeldite, and villyaellenite. Researchers have determined that a red mineral formerly known as palaite from Pala, California is only a variety of hureaulite.
Synthetics
Hydrothermal processes have produced crystals of synthetic material for chemical research purposes. However, no commercial jewelry use for these synthesized hureaulites is known.
Sources
Although gem-quality crystals are rare, many sites worldwide produce this mineral.
Notable gem-quality sources include:
- United States: Pala, California (orange masses); Branchville, Connecticut; North Groton, New Hampshire; South Dakota.
- Brazil; Haute Vienne, France; Germany; Poland; Portugal.
“Hureaulite-114927,” Hagendorf South Pegmatite (Cornelia Mine; Hagendorf South Open Cut), Hagendorf, Waidhaus, Vohenstrauß, Oberpfälzer Wald, Upper Palatinate, Bavaria, Germany, by Christian Rewitzer. Licensed under CC By-SA 3.0.
Stone Sizes
To date, no faceted gems are known. However, facetable material likely exists. One day, adventurous gem cutters will try their hands at it.
Care
You’re more likely to find hureaulites, if at all, in mineral collections than in jewelry collections. Jewelry use isn’t recommended.
Avoid exposing this very soluble material to any solutions containing acids.
Consult our Gemstone Jewelry Cleaning Guide for care recommendations.
“Hureaulite In Phosphate Nodule (Palaite),” Stewart Mine, Tourmaline Queen Mountain, Pala District, San Diego Co., California, USA. A beautiful example of a gem once thought to be “palaite.” This nodule has an outer layer of sicklerite and an inner hureaulite core. © Rob Lavinsky, www.iRocks.com. Used with permission.
IGS Newsletter
