Home > Mineral Abstracts > CanMin Vol. 13, pp. 68-74 (1975)




Vol. 13, pp. 68-74 (1975)



La yofortierite, un nouveau silicate hydraté
de manganèse de St-Hilaire, P.Q.


Guy Perrault, Yves Harvey et Raymond Pertsowsky1
Département de Génie Minéral, Ecole Polytechnique,
Case Postale 6079, Succ. A, Montréal H3C 3A7


ABSTRACT

          The chemical composition of yofortierite is:

SiO2 - 48.44
MnO - 28.41
MgO - 2.35
Al2O3 - 1.49

ZnO - 1.10
CaO - 0.90
TiO2 - 0.09
K2O - 0.05

Cr2O3 - 0.007
H2O - 17.22


          Total 100.057%. The mineral occurs as radiating fibres in pegmatite veins of the Mont St-Hilaire nepheline syenite; it is associated with analcime, serandite, eudialyte, polylithionite, aegirine, altered microcline and albite.  It is pink to violet; nx = 1.530, nz = 1.559, nx & fibre axis = 8°.  Hardness 2½, specific gravity 2.18.  Most important peaks of x-ray powder-diffractogram (Å):

10.5 (100)
3.302 (90)
2.621 (30)

2.510 (20)
4.14 (18)

     Yofortierite is the manganese analogue of palygorskite.  The following structural formula is proposed for this mineral:  Mn5Si8O20 (OH)2(OH2)4 · 4-5H2O.

     The name is derived from that of Dr. Y. O. Fortier, Canadian geo-scientist who devoted an important part of his career to the tectonics and economic geology of he Canadian arctic islands.  The name has been accepted by the IMA Commission on New Minerals and Mineral Names.

1 Du laboratoire de Minéralogie, Université de Paris VI 4, Place Jussieu, 75230 Paris Cedex 05.


© 1975  The Canadian Mineralogist