Overview

Vauxite is a rare hydrated iron–aluminum phosphate, Fe2+Al2(PO4)2(OH)2·6H2O, famed among collectors for its vivid sky- to cornflower-blue color and delicate, micaceous laths that form rosettes, fans, and crusts. The crystals are typically thin, flexible-looking laminae with pearly to silky luster, often perched on quartz or limonitic matrix. Vauxite is part of a trio with paravauxite and metavauxite; all are closely related by hydration and structure, and may occur together in the same pocket. The type locality is the Siglo Veinte Mine, Llallagua, Bolivia, which set the standard decades ago for superb blue rosette specimens. Because vauxite is uncommon and fragile, fine pieces are scarce and strongly coveted.

Popularity

Although vauxite is not a “mainstream” showstopper like tourmaline or fluorite, it is iconic in the world of rare phosphates—especially for aficionados of Bolivian classics. The brilliant blue color is unusual among phosphates and stands out instantly in a drawer. Production was always sporadic and largely historical, making the finest older pieces increasingly hard to obtain. Miniatures and small cabinets with richly crystallized rosettes on contrasting matrix are most admired; truly top pieces with large, pristine clusters are rare. Because of its rarity, color, and association with famous phosphate pockets in Bolivia, vauxite remains a hallmark species for advanced systematic and Bolivian-focused collections.

Top Collecting Localities

While vauxite has been reported from several localities, a handful produced the specimens that define the species for collectors. The best-known sources are in Bolivia’s tin–phosphate systems, where secondary phosphates formed in old mine workings and pockets.

Siglo Veinte Mine, Bolivia

Type locality and the benchmark for the species. Siglo Veinte produced the classic bright blue rosettes and radial sprays of vauxite, commonly intergrown with paravauxite and metavauxite. Aesthetic pieces show dense beds of micaceous, pearly blades perched on quartz or limonitic matrix, with superb color saturation and contrast. Many of the most famous vauxite specimens in museums and old collections trace to this mine, often with provenance to specific pockets in the mid-20th century. Pristine, richly covered matrix pieces from Siglo Veinte command a premium and set the visual standard collectors compare others against.

Huanuni Mine, Bolivia

A classic Oruro tin mine known for phosphate-rich pockets. Vauxite here is usually in delicate, pale- to medium-blue micro-rosettes and sprays scattered over drusy quartz or limonite. Individual laths can be very fine, giving a soft, silky look. While less abundant than the Siglo Veinte material, fine Huanuni pieces with crisp, undamaged rosettes remain desirable, especially when paired with contrasting matrix and companion phosphates.

Collector’s Guide

Evaluating Specimen Quality

• Color and saturation: The signature appeal is the blue color. Look for saturated sky- to cornflower blue rosettes; pale or greyed tones are less impactful. Slight color zoning can occur; evenly vivid rosettes display best.
• Crystal habit and luster: Vauxite forms thin laths as fans/rosettes with pearly to silky luster. Crisp, sharply defined blades and high sheen add value. Overly matte or “melted” looking surfaces are less attractive.
• Coverage and composition: Aesthetic specimens show generous, three-dimensional rosette coverage on contrasting matrix (quartz, limonite). Balanced compositions—clusters arranged across elevated edges or vugs—display best.
• Association: Intergrowths with paravauxite and metavauxite are classic and can enhance both scientific and aesthetic value if well-separated visually (e.g., distinct color/texture zones). Clean, complementary associations are prized.
• Size and delicacy: The species is naturally fragile; complete rosettes with intact tips are uncommon. Miniature to small-cabinet specimens with dense, undamaged coverage are top-tier. Larger plates exist but are rarer in fine condition.
• Condition: Inspect rosette rims and leading blades under bright light; tiny nicks are common but distracting if numerous. Avoid pieces with obvious crushing or with many broken, chalky blade tips unless the piece is otherwise exceptional.
• Provenance: Labels from Siglo Veinte—especially Phosphate Stope—and other documented pockets carry a premium. Historical pieces in old collections are particularly desirable.

Detecting Repairs or Treatments

• Consolidation: Because rosettes are fragile, some matrices are stabilized with dilute adhesives. Look for slight darkening “halos,” glossy patches in matrix pores, or a different sheen at the base of clusters. Minor consolidation is acceptable if disclosed.
• Reattachment: Detached rosettes may be re-glued. Under magnification, check for clear films or a meniscus at the base of sprays; UV may reveal fluorescent adhesive lines.
• Color alteration: Artificial recoloring is rare. If blue appears unnaturally uniform and plasticky, compare the luster against known references and ask for provenance. True vauxite maintains a pearly, micaceous look, not a glossy paint-like surface.
• Polishing: Uncommon for vauxite but watch for abnormally smooth, uniform “faces” on what should be micaceous blades.

Care and Storage

Vauxite is a hydrated phosphate and is more delicate than it looks. Sensible care will preserve color and integrity.

• Handling: Support matrix, not the rosettes. Avoid touching blade tips. Use both hands for cabinet specimens; place on padded, vibration-free shelves.
• Cleaning: Dust gently with a soft brush or hand blower. Avoid soaking; prolonged immersion can loosen adhesives in stabilized matrices and may promote dehydration/rehydration cycling. Never use ultrasonic or steam cleaners.
• Light and temperature: Colors are generally light-stable, but avoid prolonged direct sun and heat sources that can dehydrate the mineral (potentially promoting alteration toward metavauxite). Keep below ~35–40°C and away from hot display lights.
• Humidity: Extremely dry conditions can encourage dehydration and microcracking of delicate blades. Aim for moderate, stable indoor humidity; avoid storing next to active desiccants. Conversely, do not keep in damp environments that could affect matrix integrity.
• Transport and packing: Immobilize with soft foam around, not on, the rosettes. Ensure no contact points can abrade blade tips. For shipping, double-box with generous cushioning and label as “fragile—keep upright.”
• Long-term display: Enclosed cases with gentle LED lighting are ideal. If a specimen is known to be stabilized, avoid solvents and monitor for any adhesive aging.

By focusing on saturated blue color, crisp pearly laths, undamaged rosette rims, and classic Bolivian provenance—especially Siglo Veinte and the Phosphate Stope—you can build a top-quality vauxite suite that anchors any phosphate or Bolivia-themed collection.