Definition
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Discoverer
Etymology
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Other Categories
Trachyandesite is an extrusive igneous rock.
From French trachyandésite, trachy + andésite andesite, a lava intermediate in composition between trachyte and andesite
Durable Rock, Medium Hardness Rock
Fine Grained Rock, Opaque Rock
Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture
From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use
Fine Grained Rock, Opaque Rock