A Geoscience Digital Image Library

TitleThin section of granodiorite
DescriptionGranodiorite thin section in plain polarized light. Of the essential species, only plagioclase is euhedral. The mafics are subhedral and tend to be clustered. The quartz is undulatory. The plagioclase is strongly and complexly zoned with some thin zones selectivley sericitized. The subordinate potash feldspar is microcline perthite. Closely associated with the biotite are the accessories apatitie, zircon and magnetite. The pale green hornblende contains scattered remnants of augite. Coarse sphene is relatively abundant with some grains showing color zonign in shades of orange. Highly rounded, altered, brown grains may represent completely metamictized allanite.
LocationUSA ▹ Minnesota ▹ Stearns. Near St. Cloud.
PhotographerDarla Sondrol. 2002-03-24.
CollectionWard’s Collection of Classic North American Rocks #7.
Key wordsgranodiortie, Minnesota, thin section
Tech details948 KB. Thin section. Nikon FDX-35.
GeoDIL number2537