In some gneissic and schistose metamorphic rocks, a structure consisting of minerals like feldspar, quartz, or garnet that have been squeezed into elliptical or lens-shaped forms resembling eyes (augen), which are commonly enveloped by essentially parallel layers of contrasting constituents such as mica or chlorite. CF: augen; flaser structure. AGI
Source: Dictionary of Mining, Mineral, and Related Terms
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