SILICATES; TECTOSILICATES; FELDSPATHOID GROUP · ISOMETRIC

Nosean

Na₈Al₆Si₆O₂₄(SO₄)· H₂O

Hardness: 5.5
Streak: Light blue to white
Spec. Gravity: 2.3–2.4
System: Isometric

About

Nosean is an uncommon member of the feldspathoid group that is closely related to Lazurite and Hauyne. It can sometimes be very difficult to distinguish these three minerals without a complex chemical analysis. Nosean forms a solid solution series with Hauyne, where Hauyne contains calcium in place of some of the sodium, whereas Nosean lacks any calcium and has water in its chemical structure.
Nosean is named after German mineralogist and chemist Karl Wilhelm Nose (1753-1835).

Crystal Forms & Aggregates

As coatings on interconnected dodecahedral crystals, in octahedral crystals, as complex prismatic microcrystals, grainy, and massive.

Striking Features

Color and mode of occurrence

Environment

In alkali-rich, altered volcanic environments, nepehline syenites, and marbles.

Noteworthy Localities

Exceptional Nosean with an electric-blue color comes from Sar-e Sang, Kokcha Valley, Badakshan Province, Afghanistan, where it forms most often as a significant inclusion of Sodalite coating Nepheline. Complex, prismatic colorless microcrystals of Nosean come from the In den Dellen quarries, Niedermendig, Eifel Mountains, Germany; and well-formed microcrystals from Vetralla, Vico Lake, Viterbo Province, Latium, Italy.

Common Mineral Associations

Nepheline, Sodalite, Phlogopite, Calcite, Scapolite, Sanidine

Nosean

Abouti

Crystal Forms & Aggregatesi

Striking Featuresi

Environmenti

Noteworthy Localitiesi

Common Mineral Associationsi