Definition
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Gossan is intensely oxidized, weathered or decomposed rock, usually the upper and exposed part of an ore deposit or mineral vein.
From Cornish gossen from gos, blood from Old Cornish guit
Durable Rock, Medium Hardness Rock
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Trachyte is a grey fine-grained volcanic rock which mainly consists of alkali feldspar
Alexandre Brongniart and René Just Haüy
From Greek trakhus rough’ or trakhutēs roughness
Durable Rock, Medium Hardness Rock
Fine Grained Rock, Opaque Rock