• Webster's Revised Unabridged Dictionary
    • n Ottrelite (Min) A micaceous mineral occurring in small scales. It is characteristic of certain crystalline schists.
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Century Dictionary and Cyclopedia
    • n ottrelite A mineral occurring in small mica-like scales in a schistose rock (ottrelite schist) near Ottrez, in the Ardennes. It is a silicate of aluminium and iron with some manganese. The ottrelite group includes ottrelite proper and several related minerals, as chloritoid, sismondine, and masonite; they belong to the group of so-called brittle micas.
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Webster's Revised Unabridged Dictionary
From Ottrez, on the borders of Luxembourg