Overview

Brazilianite is a distinctive phosphate mineral known for its yellow to green hues and well‑formed prismatic crystals. It typically occurs in late‑stage, phosphate‑rich pegmatites and is prized by mineral collectors for large, gem‑quality specimens. The mineral was first described from deposits in Brazil and takes its name from that country.

Characteristics and chemistry

Brazilianite is a sodium‑aluminum phosphate hydroxide (commonly written by mineralogists as NaAl3(PO4)2(OH)4). It crystallizes in the monoclinic system and often produces elongated, striated prismatic crystals. Surface luster is vitreous to slightly pearly on cleavage surfaces. Typical physical properties include a moderate hardness (around 5.5 on the Mohs scale) and a specific gravity close to 2.9–3.0. Color ranges from pale yellow through olive and greenish yellow; transparency can be transparent to translucent, making some crystals suitable for cutting as gemstones.

Occurrence and formation

Brazilianite forms during the late stages of crystallization in granitic pegmatites, environments rich in volatiles and rare elements where phosphates and aluminous species concentrate. It is commonly associated with mica (especially muscovite), quartz, tourmaline, beryl and other phosphate minerals. Specimens frequently occur as groups of well‑formed crystals lining cavities or growing directly on sheets of muscovite, where the mica’s silvery sheen provides an attractive contrast to the brazilianite’s color.

Notable localities and history

Although named for Brazil, notable occurrences are known from several regions. Classic localities include pegmatites in Minas Gerais (for example around Conselheiro Pena and other mining districts) where large, aesthetic crystals have been recovered. Significant historic finds also come from pegmatite mines in Grafton County, New Hampshire (Palermo and Charles Davis area), which supplied many specimens to collections. Individual brazilianite crystals as large as several centimeters — and in rare cases exceeding 10 cm in length — have been documented.

Uses, collecting and distinctions

  • Collectors: Brazilianite is primarily a collector mineral; high‑quality crystals with good color and transparency command interest for display and study.
  • Gemstone use: Because of its color and clarity, some crystals are faceted into gemstones, though low hardness and perfect cleavage in places limit use in everyday jewelry.
  • Scientific interest: Its occurrence offers insights into the late‑stage chemistry and fluid evolution of pegmatites and phosphate mineral paragenesis.

Brazilianite can be confused with other yellowish phosphates or gem materials at a glance. Careful examination of crystal habit, cleavage, and context within pegmatite or on muscovite sheets helps distinguish it. Trace impurities and irradiation can subtly affect color, but the characteristic prismatic crystals and association with aluminous pegmatite minerals remain diagnostic for this attractive phosphate mineral.