Peterandresenite

Peterandresenite is a very rare mineral,^[4] the first known natural hexaniobate. Its chemical formula is Mn₄Nb₆O₁₉•14H₂O. Its structure contains a special type of octahedron: Lindqvist ion. Peterandresenite was found in a pegmatite of the Larvik complex in Norway.^[3] It is somewhat similar to other unique niobium minerals, aspedamite and menezesite.^[5][6]

Peterandresenite
General
Category	Oxide, Hexaniobate
Formula	Mn4Nb6O19•14H2O
IMA symbol	Pan[1]
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	C2/m
Unit cell	a = 15.33, b = 9.41, c = 11.28 [Å], β = 118.65° (approximated); Z = 2
Identification
Color	Orange
Crystal habit	crystals (equidimensional)
Cleavage	None
Fracture	Uneven
Tenacity	Brittle
Mohs scale hardness	2-2.5
Luster	Vitreous or resinous
Streak	Pale orange
Diaphaneity	Transparent or translucent
Density	3.05 (calc.), 3.10 (meas.) [g/cm3]
References	[2][3][4]

Occurrence

Peterandresenite was discovered in AS Granit quarry, Tvedalen, Larvik, Vestfold, Norway.^[3]