Acmite on Natrolite

Acmite (Aegerine)
Sodium Iron Silicate, NaFeSi2O6
Crystal System: Monoclinic
Hardness: 6.0-6.5
Density: 3.55-3.60

Acmite is a rock-forming mineral of the pyroxene group. It occurs primarily as a product of late crystalization of alkaline magmas. "Aegerine" is a field term used to describe pyroxenes or rocks bearing pyroxene with a large acmite component.

Natrolite
Sodium Aluminum Silicate Hydrate, Na2Al2Si3O10.2H2O
Crystal System: Orthorhombic
Hardness: 5-5.5
Density: 2.20-2.26

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, yellowish or 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

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bkeller@rockhounds.com 8/2/95