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Astrophyllite

Formula: K2NaFe2+7Ti2Si8O28(OH)4F
Colour: Bronze-yellow, golden yellow, brown to reddish brown.
Lustre: Greasy, Pearly, Sub-Metallic
Hardness:3
Specific Gravity: 3.2 - 3.4
Crystal System: Triclinic


From Água de Pau volcano, San Miguel Island, Azores District, Portugal  
Photo Serge Lavarde

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