U.S. Geological Survey Open-File Report 03-221
A Pictorial Survey of the Bedrock Beneath Western Cape Cod, Massachusetts

Thin Section of 82MW0012

Photomicrograph of Orthogneiss

A large rhombohedral sphene porphyroclast in felsic gneiss is mainly dissolved to grow biotite and epidote. Note biotite and muscovite partially rimming the sphene grain.

A large rhombohedral sphene porphyroclast in felsic gneiss (82MW0012) is mainly dissolved to grow biotite and epidote. Note biotite and muscovite partially rimming the sphene grain. Click here for a zip file with full resolution image.

bt: biotite
kfs: K-feldspar
ms: muscovite
pl: plagioclase
qtz: quartz
sph: sphene

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