Benitoite with Neptunite and Natrolite
Barium Titanium Silicate, BaTiSi3O9
Crystal System: Trigonal
- Benitoite occurs as stubby, prismatic, dipyramidal crystals in various shades of translucent
to transparent blue with a vitreous to subadamantine luster. It exhibits pleochroism; a crystal
appears blue when viewed through the acute faces and colorless when viewed through the obtuse
faces of a crystal. Benitoite fluoresces in ultraviolet light. It is associated with neptunite,
natrolite, crossite and albite.
Sodium Potassium Iron Titanium Silicate, Na2KLi(Fe,Mn)2Ti2Si8O24
Crystal System: Monoclinic
- Neptunite occurs in nepheline syenites and in cavities in nepheline pegmatites. It is associated with
benitoite and natrolite. Neptunite exhibits elongated, prismatic, black to dark brown crystals which may
be opaque or translucent.
Sodium Aluminum Silicate Hydrate, Na2Al2Si3O10.2H2O
Crystal System: Orthorhombic
- Natrolite is a member of the zeolite group. It occurs as slender, prismatic crystals with vertical
striations, usually as globular aggregates of fibrous, radiating needles. It ranges in color from
white, pink, or yellowish to transparent. It is found lining cavities in basalts and other lavas and is
associated with calcite and zeolites. Natrolite sometimes fluoresces orange in ultraviolet light.
Rocks from Martin Friedlander's Collection
Index of Specimen Images
Table of Contents