Babunaite-(Nd)

babunaite-(Nd)

almeidaite

nezilovite

chernovite-(Y)

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Formula: Nd(AsO4)
Valence: Nd(As5+O4)
Simple arsenate of neodymium, scheelite group
Crystal system: Tetragonal
Specific gravity: 5.918 calculated for the empirical formula
Hardness: 5
Streak:
Colour: Pale yellow, light yellow internal reflections
Luminescence: The crystals exhibit good visible yellow luminescence at 638 nm.
Environments

Metamorphic environments

Babunaite-(Nd) is a new mineral, approved in 2025 and to date (August 2026) reported only from the type locality.

Localities

At the type locality, the Babunaite-(Nd) type locality, Babuna Valley, Jakupica Mountains, Nežilovo, Čaška Municipality, North Macedonia, babunaite-(Nd) was discovered in muscovite-quartz schist in an area belonging to the high-grade metamorphic region of the Pelagonian Massif. A trench, in a region of massive marble, contains metasomatically altered multicoloured schists and marble-like rocks with piemontite, dolomite, baryte and Pb-Zn mineralisation. In the trench a layer of pink mica schist up to 0.5 m thick was found containing babunaite-(Nd). A few dozen metres from the babunaite-(Nd) type locality, there is a small body of metamorphosed rhyolites. The dark pink mica schists are composed of Mn-bearing muscovite and quartz, with minor braunite. Accessory minerals include hematite, gahnite, almeidaite, långbanite, zircon, piemontite, piemontite-(Pb), nežilovite, Sb-bearing rutile, fluorapatite and As-bearing fluorapatite, gasparite-(La), chernovite-(Y) (not strictly a primary metamorphic rock-forming mineral, but it can occur in metamorphic environments) and arsenoflorencite-(La).
Single crystals of babunaite-(Nd) measure up to 70 μm and often have rounded edges. The transparent, pale yellow crystals have an adamantine lustre (MM 90.3.615-624).

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