Naldrettite

Naldrettite is a mineral with a chemical formula of Pd₂Sb. It is named after Anthony J. Naldrett (born 1933), a professor at the University of Toronto, who has made significant contributions to the International Mineralogical Association (IMA). Naldrettite is a new intermetallic mineral from the Mesamax Northwest deposit, Ungava region, Québec, Canada. Mineralization takes place around the base of basaltic dyke margins. Naldrettite is economically important because of its chemical composition (Pd₂Sb). The sample in which the new mineral was discovered had high platinum group elements (PGEs) with palladium enrichment.[2]

Naldrettite
General
Category	Sulfide mineral
Formula (repeating unit)	Pd2Sb
IMA symbol	Nld[1]
Strunz classification	2.AC.25d
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) H-M Symbol: (2/m 2/m 2/m)
Space group	Cmc21
Unit cell	a = 3.3906(1), b = 17.5551(5) c = 6.957(2) [Å]; Z = 8
Identification
Color	Appears creamy white in plane-polarized light
Twinning	strain-induced polysynthetic
Fracture	Irregular
Tenacity	Ductile, Flexibly inelastic
Mohs scale hardness	4-5
Luster	metallic
Diaphaneity	opaque
Density	10.694(1) g/cm3
Refractive index	in oil 1.515
Pleochroism	non-pleochroic
Melting point	580 °C
References	[2]

Naldrettite occurs as anhedral grains that are commonly attached to sulfide minerals and are associated with clinochlore. It belongs to the orthorhombic crystal system and is a part of the pyramidal class.[2] This means that all of the edge lengths (a,b,c) of the unit cell are different in length and intersect at right angles to each other. The mineral is metallic, opaque, appears bright creamy white under plane polarized light, has weak bireflectance, and does not exhibit internal reflections.[3]