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More model informationThis rhyodacite has plagioclase and K-feldspar (likely sanidine) set in a dark glass groundmass. As such, it would be texturally described as a vitrophyre. Other minerals present are quartz along with minor hornblende and biotite - all of are invisible in hand specimen as transparent or black minerals simply vanish in the black glass groundmass (but can be identified in thin-section). The specimen is from the Carboniferous volcanic arc of the New England Orogen (Australia), and has an identical composition to this rhyodacite ignimbrite from a nearby locality. These two specimens look quite different due to different modes of eruption.
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